diff --git a/Samples/SwiftJavaExtractFFMSampleApp/src/jmh/java/org/swift/swiftkit/ffm/FFMDataBenchmark.java b/Samples/SwiftJavaExtractFFMSampleApp/src/jmh/java/org/swift/swiftkit/ffm/FFMDataBenchmark.java
index 39a64c7a9..6cac287ff 100644
--- a/Samples/SwiftJavaExtractFFMSampleApp/src/jmh/java/org/swift/swiftkit/ffm/FFMDataBenchmark.java
+++ b/Samples/SwiftJavaExtractFFMSampleApp/src/jmh/java/org/swift/swiftkit/ffm/FFMDataBenchmark.java
@@ -14,10 +14,10 @@
 
 package org.swift.swiftkit.ffm;
 
-import com.example.swift.Data;
 import com.example.swift.MySwiftLibrary;
 import org.openjdk.jmh.annotations.*;
 import org.openjdk.jmh.infra.Blackhole;
+import org.swift.swiftkit.ffm.foundation.Data;
 
 import java.lang.foreign.MemorySegment;
 import java.lang.foreign.ValueLayout;
@@ -79,7 +79,7 @@ public ByteBuffer ffm_data_withUnsafeBytes_asByteBuffer() {
       });
       return buf.value;
     }
-    
+
     @Benchmark
     public byte[] ffm_data_withUnsafeBytes_toArray() {
       Holder<byte[]> buf = new Holder<>();
diff --git a/Samples/SwiftJavaExtractFFMSampleApp/src/main/java/com/example/swift/HelloJava2Swift.java b/Samples/SwiftJavaExtractFFMSampleApp/src/main/java/com/example/swift/HelloJava2Swift.java
index 62c29482a..53fca07b6 100644
--- a/Samples/SwiftJavaExtractFFMSampleApp/src/main/java/com/example/swift/HelloJava2Swift.java
+++ b/Samples/SwiftJavaExtractFFMSampleApp/src/main/java/com/example/swift/HelloJava2Swift.java
@@ -22,6 +22,7 @@
 import org.swift.swiftkit.core.SwiftLibraries;
 import org.swift.swiftkit.ffm.AllocatingSwiftArena;
 import org.swift.swiftkit.ffm.SwiftRuntime;
+import org.swift.swiftkit.ffm.foundation.Data;
 
 import java.util.Optional;
 import java.util.OptionalLong;
@@ -85,7 +86,7 @@ static void examples() {
             var origBytes = arena.allocateFrom("foobar");
             var origDat = Data.init(origBytes, origBytes.byteSize(), arena);
             CallTraces.trace("origDat.count = " + origDat.getCount());
-            
+
             var retDat = MySwiftLibrary.globalReceiveReturnData(origDat, arena);
             retDat.withUnsafeBytes((retBytes) -> {
                 var str = retBytes.getString(0);
diff --git a/Samples/SwiftJavaExtractFFMSampleApp/src/test/java/com/example/swift/DataImportTest.java b/Samples/SwiftJavaExtractFFMSampleApp/src/test/java/com/example/swift/DataImportTest.java
index 82fb09464..69ed9db31 100644
--- a/Samples/SwiftJavaExtractFFMSampleApp/src/test/java/com/example/swift/DataImportTest.java
+++ b/Samples/SwiftJavaExtractFFMSampleApp/src/test/java/com/example/swift/DataImportTest.java
@@ -16,6 +16,7 @@
 
 import org.junit.jupiter.api.Test;
 import org.swift.swiftkit.ffm.AllocatingSwiftArena;
+import org.swift.swiftkit.ffm.foundation.Data;
 
 import java.lang.foreign.ValueLayout;
 
@@ -134,7 +135,7 @@ void test_Data_toByteBuffer_emptyData() {
             byte[] original = new byte[0];
             var data = Data.fromByteArray(original, arena);
             var buffer = data.toByteBuffer(arena);
-            
+
             assertEquals(0, buffer.capacity());
         }
     }
diff --git a/Samples/SwiftJavaExtractFFMSampleApp/src/test/java/com/example/swift/OptionalImportTest.java b/Samples/SwiftJavaExtractFFMSampleApp/src/test/java/com/example/swift/OptionalImportTest.java
index 57e8dba61..306ce688c 100644
--- a/Samples/SwiftJavaExtractFFMSampleApp/src/test/java/com/example/swift/OptionalImportTest.java
+++ b/Samples/SwiftJavaExtractFFMSampleApp/src/test/java/com/example/swift/OptionalImportTest.java
@@ -16,6 +16,7 @@
 
 import org.junit.jupiter.api.Test;
 import org.swift.swiftkit.ffm.AllocatingSwiftArena;
+import org.swift.swiftkit.ffm.foundation.Data;
 
 import java.util.Optional;
 import java.util.OptionalLong;
diff --git a/Samples/SwiftJavaExtractJNISampleApp/src/jmh/java/com/example/swift/JNIDataBenchmark.java b/Samples/SwiftJavaExtractJNISampleApp/src/jmh/java/com/example/swift/JNIDataBenchmark.java
index 283f1f7c0..52b1d16b8 100644
--- a/Samples/SwiftJavaExtractJNISampleApp/src/jmh/java/com/example/swift/JNIDataBenchmark.java
+++ b/Samples/SwiftJavaExtractJNISampleApp/src/jmh/java/com/example/swift/JNIDataBenchmark.java
@@ -18,6 +18,7 @@
 import org.openjdk.jmh.infra.Blackhole;
 import org.swift.swiftkit.core.ClosableSwiftArena;
 import org.swift.swiftkit.core.SwiftArena;
+import org.swift.swiftkit.core.foundation.Data;
 
 import java.util.concurrent.TimeUnit;
 
diff --git a/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/DataTest.java b/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/DataTest.java
index a6024ca12..32bd4a98b 100644
--- a/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/DataTest.java
+++ b/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/DataTest.java
@@ -16,6 +16,7 @@
 
 import org.junit.jupiter.api.Test;
 import org.swift.swiftkit.core.SwiftArena;
+import org.swift.swiftkit.core.foundation.Data;
 
 import static org.junit.jupiter.api.Assertions.*;
 
diff --git a/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/DateTest.java b/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/DateTest.java
index 9b13f37ec..36da11d9d 100644
--- a/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/DateTest.java
+++ b/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/DateTest.java
@@ -16,6 +16,7 @@
 
 import org.junit.jupiter.api.Test;
 import org.swift.swiftkit.core.SwiftArena;
+import org.swift.swiftkit.core.foundation.Date;
 
 import java.time.Instant;
 import java.time.temporal.ChronoUnit;
@@ -59,4 +60,4 @@ void date_timeIntervalSince1970() {
             assertEquals(1000, date.getTimeIntervalSince1970());
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/OptionalsTest.java b/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/OptionalsTest.java
index 771cffc33..941d2a545 100644
--- a/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/OptionalsTest.java
+++ b/Samples/SwiftJavaExtractJNISampleApp/src/test/java/com/example/swift/OptionalsTest.java
@@ -14,9 +14,10 @@
 
 package com.example.swift;
 
-import com.example.swift.MySwiftLibrary;
 import org.junit.jupiter.api.Test;
 import org.swift.swiftkit.core.SwiftArena;
+import org.swift.swiftkit.core.foundation.Data;
+import org.swift.swiftkit.core.foundation.Date;
 
 import java.time.Instant;
 import java.util.Optional;
@@ -143,4 +144,4 @@ void optionalThrows() {
             assertEquals("swiftError", exception.getMessage());
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+FoundationData.swift b/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+FoundationData.swift
deleted file mode 100644
index 7dd054f22..000000000
--- a/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+FoundationData.swift
+++ /dev/null
@@ -1,166 +0,0 @@
-//===----------------------------------------------------------------------===//
-//
-// This source file is part of the Swift.org open source project
-//
-// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
-// Licensed under Apache License v2.0
-//
-// See LICENSE.txt for license information
-// See CONTRIBUTORS.txt for the list of Swift.org project authors
-//
-// SPDX-License-Identifier: Apache-2.0
-//
-//===----------------------------------------------------------------------===//
-
-import CodePrinting
-import SwiftJavaConfigurationShared
-import SwiftJavaJNICore
-import SwiftSyntax
-import SwiftSyntaxBuilder
-
-import struct Foundation.URL
-
-extension FFMSwift2JavaGenerator {
-
-  /// Print Java helper methods for Foundation.Data type
-  package func printFoundationDataHelpers(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
-    let typeName = decl.swiftNominal.name
-    let thunkNameCopyBytes = "swiftjava_\(swiftModuleName)_\(typeName)_copyBytes__"
-
-    printer.printSeparator("\(typeName) helper methods")
-
-    // This is primarily here for API parity with the JNI version and easier discovery
-    printer.print(
-      """
-      /**
-       * Creates a new Swift {@link \(typeName)} instance from a byte array.
-       *
-       * @param bytes The byte array to copy into the \(typeName)
-       * @param arena The arena for memory management
-       * @return A new \(typeName) instance containing a copy of the bytes
-       */
-      public static \(typeName) fromByteArray(byte[] bytes, AllocatingSwiftArena arena) {
-        Objects.requireNonNull(bytes, "bytes cannot be null");
-        return \(typeName).init(bytes, arena);
-      }
-      """
-    )
-
-    // TODO: Implement a fromByteBuffer as well
-
-    // Print the descriptor class for copyBytes native call using the shared helper
-    let copyBytesCFunc = CFunction(
-      resultType: .void,
-      name: thunkNameCopyBytes,
-      parameters: [
-        CParameter(name: "self", type: .qualified(const: true, volatile: false, type: .pointer(.void))),
-        CParameter(name: "destination", type: .pointer(.void)),
-        CParameter(name: "count", type: .integral(.ptrdiff_t)),
-      ],
-      isVariadic: false
-    )
-    printJavaBindingDescriptorClass(&printer, copyBytesCFunc)
-
-    printer.print(
-      """
-      /**
-       * Copies the contents of this \(typeName) to a new {@link MemorySegment}.
-       *
-       * This is the most efficient way to access \(typeName) bytes from Java when you don't
-       * need a {@code byte[]}. The returned segment is valid for the lifetime of the arena.
-       *
-       * <p>Copy count: 1 (Swift Data -> MemorySegment)
-       *
-       * @param arena The arena to allocate the segment in
-       * @return A MemorySegment containing a copy of this \(typeName)'s bytes
-       */
-      public MemorySegment toMemorySegment(AllocatingSwiftArena arena) {
-        $ensureAlive();
-        long count = getCount();
-        if (count == 0) return MemorySegment.NULL;
-        MemorySegment segment = arena.allocate(count);
-        \(thunkNameCopyBytes).call(this.$memorySegment(), segment, count);
-        return segment;
-      }
-      """
-    )
-
-    printer.print(
-      """
-      /**
-       * Copies the contents of this \(typeName) to a new {@link ByteBuffer}.
-       *
-       * The returned {@link java.nio.ByteBuffer} is a view over native memory and is valid for the
-       * lifetime of the arena. This avoids an additional copy to the Java heap.
-       *
-       * <p>Copy count: 1 (Swift Data -> native memory (managed by passed arena), then zero-copy view)
-       *
-       * @param arena The arena to allocate the underlying memory in
-       * @return A ByteBuffer view of the copied bytes
-       */
-      public java.nio.ByteBuffer toByteBuffer(AllocatingSwiftArena arena) {
-        $ensureAlive();
-        long count = getCount();
-        if (count == 0) return java.nio.ByteBuffer.allocate(0);
-        MemorySegment segment = arena.allocate(count);
-        \(thunkNameCopyBytes).call(this.$memorySegment(), segment, count);
-        return segment.asByteBuffer();
-      }
-      """
-    )
-
-    printer.print(
-      """
-      /**
-       * Copies the contents of this \(typeName) to a new byte array.
-       * The lifetime of the array is independent of the arena, the arena is just used for an intermediary copy.
-       *
-       * <p>Copy count: 2 (Swift Data -> MemorySegment -> byte[])
-       *
-       * <p>For better performance when you can work with {@link MemorySegment} or
-       * {@link java.nio.ByteBuffer}, prefer {@link #toMemorySegment} or {@link #toByteBuffer}.
-       *
-       * @param arena The arena to use for temporary native memory allocation
-       * @return A byte array containing a copy of this \(typeName)'s bytes
-       */
-      public byte[] toByteArray(AllocatingSwiftArena arena) {
-        $ensureAlive();
-        long count = getCount();
-        if (count == 0) return new byte[0];
-        MemorySegment segment = arena.allocate(count);
-        \(thunkNameCopyBytes).call(this.$memorySegment(), segment, count);
-        return segment.toArray(ValueLayout.JAVA_BYTE);
-      }
-      """
-    )
-
-    printer.print(
-      """
-      /**
-       * Copies the contents of this \(typeName) to a new byte array.
-       * The lifetime of the array is independent of the arena, the arena is just used for an intermediary copy.
-       *
-       * This is a convenience method that creates a temporary arena for the copy.
-       * For repeated calls, prefer {@link #toByteArray(AllocatingSwiftArena)} to reuse an arena.
-       *
-       * <p>Copy count: 2 (Swift Data -> MemorySegment -> byte[])
-       *
-       * <p>For better performance when you can work with {@link MemorySegment} or
-       * {@link java.nio.ByteBuffer}, prefer {@link #toMemorySegment} or {@link #toByteBuffer}.
-       *
-       * @return A byte array containing a copy of this \(typeName)'s bytes
-       */
-      public byte[] toByteArray() {
-        $ensureAlive();
-        long count = getCount();
-        if (count == 0) return new byte[0];
-        try (var arena = Arena.ofConfined()) {
-          MemorySegment segment = arena.allocate(count);
-          \(thunkNameCopyBytes).call(this.$memorySegment(), segment, count);
-          return segment.toArray(ValueLayout.JAVA_BYTE);
-        }
-      }
-      """
-    )
-  }
-}
diff --git a/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaBindingsPrinting.swift b/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaBindingsPrinting.swift
index cb7eac727..1385894d3 100644
--- a/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaBindingsPrinting.swift
+++ b/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaBindingsPrinting.swift
@@ -456,6 +456,8 @@ extension FFMSwift2JavaGenerator {
       let arena =
         if let className = type.className,
           analysis.importedTypes[className] != nil
+            || type == .swiftkitFFMFoundationData
+            || type == .swiftkitFFMFoundationDataProtocol
         {
           // Use passed-in 'SwiftArena' for 'SwiftValue'.
           "swiftArena"
@@ -619,7 +621,9 @@ extension FFMSwift2JavaGenerator {
   func renderMemoryLayoutValue(for javaType: JavaType) -> String {
     if let layout = ForeignValueLayout(javaType: javaType) {
       return layout.description
-    } else if case .class(package: _, name: let customClass, _) = javaType {
+    } else if case .class(.some(let package), name: let customClass, _) = javaType {
+      return ForeignValueLayout(customType: "\(package).\(customClass)").description
+    } else if case .class(.none, name: let customClass, _) = javaType {
       return ForeignValueLayout(customType: customClass).description
     } else {
       fatalError("renderMemoryLayoutValue not supported for \(javaType)")
@@ -776,7 +780,7 @@ extension FFMSwift2JavaGenerator.JavaConversionStep {
 
     case .wrapMemoryAddressUnsafe(let inner, let javaType):
       let inner = inner.render(&printer, placeholder, placeholderForDowncall: placeholderForDowncall)
-      return "\(javaType.className!).wrapMemoryAddressUnsafe(\(inner), swiftArena)"
+      return "\(javaType).wrapMemoryAddressUnsafe(\(inner), swiftArena)"
 
     case .construct(let inner, let javaType):
       let inner = inner.render(&printer, placeholder, placeholderForDowncall: placeholderForDowncall)
diff --git a/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaTranslation.swift b/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaTranslation.swift
index c750fdc0a..e4363b7a4 100644
--- a/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaTranslation.swift
+++ b/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator+JavaTranslation.swift
@@ -464,7 +464,15 @@ extension FFMSwift2JavaGenerator {
             )
 
           case .foundationData, .essentialsData:
-            break
+            return TranslatedParameter(
+              javaParameters: [
+                JavaParameter(
+                  name: parameterName,
+                  type: .swiftkitFFMFoundationData
+                )
+              ],
+              conversion: .swiftValueSelfSegment(.placeholder)
+            )
 
           case .swiftJavaError:
             // SwiftJavaError is a class — treat as arbitrary nominal type below
@@ -635,10 +643,26 @@ extension FFMSwift2JavaGenerator {
       case .nominal(let nominal):
         if let knownType = nominal.nominalTypeDecl.knownTypeKind {
           switch knownType {
-          case .foundationData, .foundationDataProtocol:
-            break
-          case .essentialsData, .essentialsDataProtocol:
-            break
+          case .foundationData, .essentialsData:
+            return TranslatedParameter(
+              javaParameters: [
+                JavaParameter(
+                  name: parameterName,
+                  type: .optional(.swiftkitFFMFoundationData)
+                )
+              ],
+              conversion: .call(.placeholder, function: "SwiftRuntime.toOptionalSegmentInstance", withArena: false)
+            )
+          case .foundationDataProtocol, .essentialsDataProtocol:
+            return TranslatedParameter(
+              javaParameters: [
+                JavaParameter(
+                  name: parameterName,
+                  type: .optional(.swiftkitFFMFoundationDataProtocol)
+                )
+              ],
+              conversion: .call(.placeholder, function: "SwiftRuntime.toOptionalSegmentInstance", withArena: false)
+            )
           default:
             throw JavaTranslationError.unhandledType(known: .optional(swiftType))
           }
@@ -647,7 +671,7 @@ extension FFMSwift2JavaGenerator {
         let translatedTy = try self.translate(swiftType: swiftType)
         return TranslatedParameter(
           javaParameters: [
-            JavaParameter(name: parameterName, type: JavaType(className: "Optional<\(translatedTy.description)>"))
+            JavaParameter(name: parameterName, type: .optional(translatedTy))
           ],
           conversion: .call(.placeholder, function: "SwiftRuntime.toOptionalSegmentInstance", withArena: false)
         )
@@ -750,7 +774,15 @@ extension FFMSwift2JavaGenerator {
             )
 
           case .foundationData, .essentialsData:
-            break // Implemented as wrapper
+            let javaType: JavaType = .swiftkitFFMFoundationData
+            return TranslatedResult(
+              javaResultType: javaType,
+              annotations: resultAnnotations,
+              outParameters: [
+                JavaParameter(name: "", type: javaType)
+              ],
+              conversion: .wrapMemoryAddressUnsafe(.placeholder, javaType)
+            )
 
           case .unsafePointer, .unsafeMutablePointer:
             // FIXME: Implement
diff --git a/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator.swift b/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator.swift
index 41c063048..4572316c3 100644
--- a/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator.swift
+++ b/Sources/JExtractSwiftLib/FFM/FFMSwift2JavaGenerator.swift
@@ -328,9 +328,6 @@ extension FFMSwift2JavaGenerator {
         printFunctionDowncallMethods(&printer, funcDecl)
       }
 
-      // Special helper methods for known types (e.g. Data)
-      printSpecificTypeHelpers(&printer, decl)
-
       if let printSpecialPostExtras = self.getSpecialNominalPostMembersPrinting(decl) {
         printSpecialPostExtras(&printer)
       } else {
@@ -555,20 +552,6 @@ extension FFMSwift2JavaGenerator {
     )
   }
 
-  /// Print special helper methods for known types like Foundation.Data
-  func printSpecificTypeHelpers(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
-    guard let knownType = decl.swiftNominal.knownTypeKind else {
-      return
-    }
-
-    switch knownType {
-    case .foundationData, .essentialsData:
-      printFoundationDataHelpers(&printer, decl)
-    default:
-      break
-    }
-  }
-
   /// Print the `fetchDescription` static helper for SwiftJavaError.
   /// This calls the `errorDescription()` downcall to get the error message
   /// for the super constructor
diff --git a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift
index e6b3c71b8..833aabbcd 100644
--- a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift
+++ b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaBindingsPrinting.swift
@@ -314,8 +314,6 @@ extension JNISwift2JavaGenerator {
         printer.println()
       }
 
-      printSpecificTypeHelpers(&printer, decl)
-
       printTypeMetadataAddressFunction(&printer, decl)
       printer.println()
 
@@ -336,22 +334,6 @@ extension JNISwift2JavaGenerator {
     }
   }
 
-  /// Prints helpers for specific types like `Foundation.Date`
-  private func printSpecificTypeHelpers(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
-    guard let knownType = decl.swiftNominal.knownTypeKind else { return }
-
-    switch knownType {
-    case .foundationDate, .essentialsDate:
-      printFoundationDateHelpers(&printer, decl)
-
-    case .foundationData, .essentialsData:
-      printFoundationDataHelpers(&printer, decl)
-
-    default:
-      break
-    }
-  }
-
   private func printHeader(_ printer: inout CodePrinter) {
     printer.print(
       """
@@ -616,7 +598,7 @@ extension JNISwift2JavaGenerator {
       }
       generics.append((name, extends))
     }
-    .map { "\($0) extends \($1.compactMap(\.className).joined(separator: " & "))" }
+    .map { "\($0) extends \($1.compactMap(\.description).joined(separator: " & "))" }
     .joined(separator: ", ")
 
     if !generics.isEmpty {
@@ -832,117 +814,4 @@ extension JNISwift2JavaGenerator {
       }
     }
   }
-
-  private func printFoundationDateHelpers(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
-    printer.print(
-      """
-      /**
-       * Converts this wrapped date to a Java {@link java.time.Instant}.
-       * <p>
-       * This method constructs the {@code Instant} using the underlying {@code double} value
-       * representing seconds since the Unix Epoch (January 1, 1970).
-       * </p>
-       *
-       * @return A {@code java.time.Instant} derived from the floating-point timestamp.
-       */
-      public java.time.Instant toInstant() {
-          long seconds = (long) this.getTimeIntervalSince1970();
-          long nanos = Math.round((this.getTimeIntervalSince1970() - seconds) * 1_000_000_000);
-          return java.time.Instant.ofEpochSecond(seconds, nanos);
-      }
-      """
-    )
-    printer.println()
-    printer.print(
-      """
-      /**
-       * Initializes a Swift {@code Foundation.Date} from a Java {@link java.time.Instant}.
-       *
-       * <h3>Warning: Precision Loss</h3>
-       * <p>
-       * <strong>The input precision will be degraded.</strong>
-       * </p>
-       * <p>
-       * Java's {@code Instant} stores time with <strong>nanosecond</strong> precision (9 decimal places).
-       * However, this class stores time as a 64-bit floating-point value.
-       * </p>
-       * <p>
-       * This leaves enough capacity for <strong>microsecond</strong> precision (approx. 6 decimal places).
-       * </p>
-       * <p>
-       * Consequently, the last ~3 digits of the {@code Instant}'s nanosecond field will be
-       * truncated or subjected to rounding errors during conversion.
-       * </p>
-       *
-       * @param instant The source timestamp to convert.
-       * @return A date derived from the input instant with microsecond precision.
-       */
-      public static Date fromInstant(java.time.Instant instant, SwiftArena swiftArena) {
-        Objects.requireNonNull(instant, "Instant cannot be null");
-        double timeIntervalSince1970 = instant.getEpochSecond() + (instant.getNano() / 1_000_000_000.0);
-        return Date.init(timeIntervalSince1970, swiftArena);
-      }
-      """
-    )
-  }
-
-  private func printFoundationDataHelpers(_ printer: inout CodePrinter, _ decl: ImportedNominalType) {
-    printer.print(
-      """
-      /**
-       * Creates a new Swift @{link Data} instance from a byte array.
-       *
-       * @param bytes The byte array to copy into the Data
-       * @param swiftArena The arena for memory management
-       * @return A new Data instance containing a copy of the bytes
-       */
-      public static Data fromByteArray(byte[] bytes, SwiftArena swiftArena) {
-        Objects.requireNonNull(bytes, "bytes cannot be null");
-        return Data.init(bytes, swiftArena);
-      }
-      """
-    )
-
-    printer.print(
-      """
-      /**
-       * Copies the contents of this Data to a new byte array.
-       * 
-       * This is a relatively efficient implementation, which avoids native array copies,
-       * however it will still perform a copy of the data onto the JVM heap, so use this 
-       * only when necessary.
-       * 
-       * </p> When utmost performance is necessary, you may want to investigate the FFM mode
-       * of jextract which is able to map memory more efficiently. 
-       *
-       * @return A byte array containing a copy of this Data's bytes
-       */
-      public byte[] toByteArray() {
-        return $toByteArray(this.$memoryAddress());
-      }
-      """
-    )
-
-    printer.print(
-      """
-      private static native byte[] $toByteArray(long selfPointer);
-
-      /**
-       * Copies the contents of this Data to a new byte array.
-       * 
-       * @deprecated Prefer using the `toByteArray` method as it is more performant.
-       * This implementation uses a naive conversion path from native bytes into jbytes 
-       * and then copying them onto the jvm heap.
-       * 
-       * @return A byte array containing a copy of this Data's bytes
-       */
-      @Deprecated(forRemoval = true)
-      public byte[] toByteArrayIndirectCopy() {
-        return $toByteArrayIndirectCopy(this.$memoryAddress());
-      }
-
-      private static native byte[] $toByteArrayIndirectCopy(long selfPointer);
-      """
-    )
-  }
 }
diff --git a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaTranslation.swift b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaTranslation.swift
index 69455ba69..f5ce801cc 100644
--- a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaTranslation.swift
+++ b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+JavaTranslation.swift
@@ -176,7 +176,7 @@ extension JNISwift2JavaGenerator {
             ),
           parameters: [],
           resultType: TranslatedResult(
-            javaType: .class(package: nil, name: "Optional", typeParameters: [.class(package: nil, name: caseName)]),
+            javaType: .optional(.class(package: nil, name: caseName)),
             outParameters: conversions.flatMap(\.translated.outParameters),
             conversion: enumCase.parameters.isEmpty
               ? constructRecordConversion
@@ -505,10 +505,24 @@ extension JNISwift2JavaGenerator {
             )
 
           case .foundationDate, .essentialsDate:
-            break // Handled as wrapped struct
+            return TranslatedParameter(
+              parameter: JavaParameter(
+                name: parameterName,
+                type: .concrete(.swiftkitCoreFoundationDate),
+                annotations: parameterAnnotations,
+              ),
+              conversion: .valueMemoryAddress(.placeholder),
+            )
 
           case .foundationData, .essentialsData:
-            break // Handled as wrapped struct
+            return TranslatedParameter(
+              parameter: JavaParameter(
+                name: parameterName,
+                type: .concrete(.swiftkitCoreFoundationData),
+                annotations: parameterAnnotations,
+              ),
+              conversion: .valueMemoryAddress(.placeholder),
+            )
 
           case .unsafeRawBufferPointer, .unsafeMutableRawBufferPointer:
             return TranslatedParameter(
@@ -872,7 +886,7 @@ extension JNISwift2JavaGenerator {
         return TranslatedParameter(
           parameter: JavaParameter(
             name: parameterName,
-            type: .class(package: nil, name: "Optional", typeParameters: [javaType]),
+            type: .optional(javaType),
             annotations: parameterAnnotations,
           ),
           conversion: .method(
@@ -945,12 +959,22 @@ extension JNISwift2JavaGenerator {
             )
 
           case .foundationDate, .essentialsDate:
-            // Handled as wrapped struct
-            break
+            let javaType = JavaType.swiftkitCoreFoundationDate
+            return TranslatedResult(
+              javaType: javaType,
+              annotations: resultAnnotations,
+              outParameters: [],
+              conversion: .wrapMemoryAddressUnsafe(.placeholder, javaType),
+            )
 
           case .foundationData, .essentialsData:
-            // Handled as wrapped struct
-            break
+            let javaType = JavaType.swiftkitCoreFoundationData
+            return TranslatedResult(
+              javaType: javaType,
+              annotations: resultAnnotations,
+              outParameters: [],
+              conversion: .wrapMemoryAddressUnsafe(.placeholder, javaType),
+            )
 
           case .foundationUUID, .essentialsUUID:
             return TranslatedResult(
@@ -1053,7 +1077,7 @@ extension JNISwift2JavaGenerator {
               genericParameters: genericParameters,
               genericRequirements: genericRequirements,
             )
-            return .class(package: "java.util", name: "Optional", typeParameters: [wrappedType])
+            return .optional(wrappedType)
 
           case .array:
             guard let elementType = nominalType.genericArguments?.first else {
@@ -1094,13 +1118,13 @@ extension JNISwift2JavaGenerator {
             return .swiftSet(elementJavaType)
 
           case .foundationDate, .essentialsDate:
-            return .class(package: nil, name: "Date")
+            return .swiftkitCoreFoundationDate
 
           case .foundationData, .essentialsData:
-            return .class(package: nil, name: "Data")
+            return .swiftkitCoreFoundationData
 
           case .foundationDataProtocol, .essentialsDataProtocol:
-            return .class(package: nil, name: "DataProtocol")
+            return .swiftkitCoreFoundationDataProtocol
 
           case .foundationUUID, .essentialsUUID:
             return .javaUtilUUID
@@ -1162,7 +1186,6 @@ extension JNISwift2JavaGenerator {
       genericParameters: [SwiftGenericParameterDeclaration],
       genericRequirements: [SwiftGenericRequirement],
     ) throws -> TranslatedResult {
-      let arity = elements.count
       var outParameters: [OutParameter] = []
       var elementOutParamNames: [String] = []
       var elementConversions: [JavaNativeConversionStep] = []
@@ -1338,7 +1361,7 @@ extension JNISwift2JavaGenerator {
             .void
           }
 
-        let returnType = JavaType.class(package: nil, name: "Optional", typeParameters: [javaType])
+        let returnType = JavaType.optional(javaType)
         return TranslatedResult(
           javaType: returnType,
           annotations: parameterAnnotations,
@@ -1854,16 +1877,22 @@ extension JNISwift2JavaGenerator {
 
       case .wrapMemoryAddressUnsafe(let inner, let javaType):
         let inner = inner.render(&printer, placeholder)
-        guard case .class(_, let className, let typeParameters) = javaType else {
+        guard case .class(let package, let className, let typeParameters) = javaType else {
           fatalError("\(javaType) is not class.")
         }
+        let packagePart: String =
+          if let package {
+            "\(package)."
+          } else {
+            ""
+          }
         let genericClause =
           if !typeParameters.isEmpty {
             "<\(typeParameters.map(\.description).joined(separator: ", "))>"
           } else {
             ""
           }
-        return "\(className).\(genericClause)wrapMemoryAddressUnsafe(\(inner), swiftArena)"
+        return "\(packagePart)\(className).\(genericClause)wrapMemoryAddressUnsafe(\(inner), swiftArena)"
 
       case .constructJavaClass(let inner, let javaType):
         let inner = inner.render(&printer, placeholder)
diff --git a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
index 544b1b5ac..24c106c01 100644
--- a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
+++ b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
@@ -347,7 +347,6 @@ extension JNISwift2JavaGenerator {
       printer.println()
     }
 
-    printSpecificTypeThunks(&printer, type)
     printTypeMetadataAddressThunk(&printer, type)
     printer.println()
   }
@@ -856,67 +855,6 @@ extension JNISwift2JavaGenerator {
     }
   }
 
-  /// Prints thunks for specific known types like Foundation.Date, Foundation.Data
-  private func printSpecificTypeThunks(_ printer: inout CodePrinter, _ type: ImportedNominalType) {
-    guard let knownType = type.swiftNominal.knownTypeKind else { return }
-
-    switch knownType {
-    case .foundationData, .essentialsData:
-      printFoundationDataThunks(&printer, type)
-      printer.println()
-
-    default:
-      break
-    }
-  }
-
-  /// Prints Swift thunks for Foundation.Data helper methods
-  private func printFoundationDataThunks(_ printer: inout CodePrinter, _ type: ImportedNominalType) {
-    let selfPointerParam = JavaParameter(name: "selfPointer", type: .long)
-    let parentName = type.qualifiedName
-
-    // Rebind the memory instead of converting, and set the memory directly using 'jniSetArrayRegion' from the buffer
-    printCDecl(
-      &printer,
-      javaMethodName: "$toByteArray",
-      parentName: type.effectiveJavaName,
-      parameters: [
-        selfPointerParam
-      ],
-      resultType: .array(.byte),
-    ) { printer in
-      let selfVar = self.printSelfJLongToUnsafeMutablePointer(&printer, swiftParentName: parentName, selfPointerParam)
-
-      printer.print(
-        """
-        return \(selfVar).pointee.withUnsafeBytes { buffer in
-          return buffer.getJNIValue(in: environment)
-        }
-        """
-      )
-    }
-
-    // Legacy API, also to compare with as a baseline, we could remove it
-    printCDecl(
-      &printer,
-      javaMethodName: "$toByteArrayIndirectCopy",
-      parentName: type.effectiveJavaName,
-      parameters: [
-        selfPointerParam
-      ],
-      resultType: .array(.byte),
-    ) { printer in
-      let selfVar = self.printSelfJLongToUnsafeMutablePointer(&printer, swiftParentName: parentName, selfPointerParam)
-
-      printer.print(
-        """
-        // This is a double copy, we need to initialize the array and then copy into a JVM array in getJNIValue
-        return [UInt8](\(selfVar).pointee).getJNIValue(in: environment)
-        """
-      )
-    }
-  }
-
   private func printFunctionOpenerCall(_ printer: inout CodePrinter, _ decl: ImportedFunc) {
     guard let translatedDecl = self.translatedDecl(for: decl) else {
       fatalError("Cannot print function opener for a function that can't be translated: \(decl)")
diff --git a/Sources/JExtractSwiftLib/JavaTypes/JavaType+JDK.swift b/Sources/JExtractSwiftLib/JavaTypes/JavaType+JDK.swift
index 34cb7f458..246f8a8b1 100644
--- a/Sources/JExtractSwiftLib/JavaTypes/JavaType+JDK.swift
+++ b/Sources/JExtractSwiftLib/JavaTypes/JavaType+JDK.swift
@@ -45,6 +45,11 @@ extension JavaType {
     .class(package: "java.lang", name: "Object")
   }
 
+  /// The description of the type java.util.Optional..
+  static func optional(_ T: JavaType) -> JavaType {
+    .class(package: "java.util", name: "Optional", typeParameters: [T])
+  }
+
   /// The description of the type java.util.concurrent.CompletableFuture<T>
   static func completableFuture(_ T: JavaType) -> JavaType {
     .class(package: "java.util.concurrent", name: "CompletableFuture", typeParameters: [T.boxedType])
@@ -59,4 +64,23 @@ extension JavaType {
     .class(package: "java.util", name: "UUID")
   }
 
+  static var swiftkitCoreFoundationDate: JavaType {
+    .class(package: "org.swift.swiftkit.core.foundation", name: "Date")
+  }
+
+  static var swiftkitCoreFoundationData: JavaType {
+    .class(package: "org.swift.swiftkit.core.foundation", name: "Data")
+  }
+
+  static var swiftkitCoreFoundationDataProtocol: JavaType {
+    .class(package: "org.swift.swiftkit.core.foundation", name: "DataProtocol")
+  }
+
+  static var swiftkitFFMFoundationData: JavaType {
+    .class(package: "org.swift.swiftkit.ffm.foundation", name: "Data")
+  }
+
+  static var swiftkitFFMFoundationDataProtocol: JavaType {
+    .class(package: "org.swift.swiftkit.ffm.foundation", name: "DataProtocol")
+  }
 }
diff --git a/Sources/JExtractSwiftLib/Swift2JavaTranslator.swift b/Sources/JExtractSwiftLib/Swift2JavaTranslator.swift
index 106247a48..5ac2384d7 100644
--- a/Sources/JExtractSwiftLib/Swift2JavaTranslator.swift
+++ b/Sources/JExtractSwiftLib/Swift2JavaTranslator.swift
@@ -127,39 +127,6 @@ extension Swift2JavaTranslator {
 
     // Apply any specializations registered after their target types were visited
     visitor.applyPendingSpecializations()
-
-    self.visitFoundationDeclsIfNeeded(with: visitor)
-  }
-
-  private func visitFoundationDeclsIfNeeded(with visitor: Swift2JavaVisitor) {
-    // If any API uses 'Foundation.Data' or 'FoundationEssentials.Data',
-    // import 'Data' as if it's declared in this module.
-    if let dataDecl = self.symbolTable[.foundationData] ?? self.symbolTable[.essentialsData] {
-      let dataProtocolDecl = (self.symbolTable[.foundationDataProtocol] ?? self.symbolTable[.essentialsDataProtocol])!
-      if self.isUsing(where: { $0 == dataDecl || $0 == dataProtocolDecl }) {
-        visitor.visit(
-          nominalDecl: dataDecl.syntax!.asNominal!,
-          in: nil,
-          sourceFilePath: "Foundation/FAKE_FOUNDATION_DATA.swift",
-        )
-        visitor.visit(
-          nominalDecl: dataProtocolDecl.syntax!.asNominal!,
-          in: nil,
-          sourceFilePath: "Foundation/FAKE_FOUNDATION_DATAPROTOCOL.swift",
-        )
-      }
-    }
-
-    // Foundation.Date
-    if let dateDecl = self.symbolTable[.foundationDate] ?? self.symbolTable[.essentialsDate] {
-      if self.isUsing(where: { $0 == dateDecl }) {
-        visitor.visit(
-          nominalDecl: dateDecl.syntax!.asNominal!,
-          in: nil,
-          sourceFilePath: "Foundation/FAKE_FOUNDATION_DATE.swift",
-        )
-      }
-    }
   }
 
   package func prepareForTranslation() {
diff --git a/Sources/SwiftJavaRuntimeSupport/Foundation/Data+JNI.swift b/Sources/SwiftJavaRuntimeSupport/Foundation/Data+JNI.swift
new file mode 100644
index 000000000..2451ccd0b
--- /dev/null
+++ b/Sources/SwiftJavaRuntimeSupport/Foundation/Data+JNI.swift
@@ -0,0 +1,86 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftJava
+import SwiftJavaJNICore
+
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
+@JavaImplementation("org.swift.swiftkit.core.foundation.Data")
+extension Data {
+  @JavaMethod("$init")
+  static func _init(environment: UnsafeMutablePointer<JNIEnv?>!, bytes: [UInt8]) -> Int64 {
+    let result$ = UnsafeMutablePointer<Data>.allocate(capacity: 1)
+    result$.initialize(to: Data(bytes))
+    return Int64(Int(bitPattern: result$))
+  }
+
+  @JavaMethod("$getCount")
+  static func _getCount(environment: UnsafeMutablePointer<JNIEnv?>!, selfPointer: Int64) -> Int64 {
+    let selfPointer$ = UnsafeMutablePointer<Data>(bitPattern: Int(selfPointer))
+    guard let selfPointer$ else {
+      fatalError("selfPointer memory address was null in call to \(#function)!")
+    }
+    return Int64(selfPointer$.pointee.count)
+  }
+
+  @JavaMethod("$typeMetadataAddressDowncall")
+  static func _typeMetadataAddressDowncall(environment: UnsafeMutablePointer<JNIEnv?>!) -> Int64 {
+    let metadataPointer = unsafeBitCast(Data.self, to: UnsafeRawPointer.self)
+    return Int64(Int(bitPattern: metadataPointer))
+  }
+}
+
+#if compiler(>=6.3)
+@used
+#endif
+@_cdecl("Java_org_swift_swiftkit_core_foundation_Data__00024toByteArray__J")
+public func Java_org_swift_swiftkit_core_foundation_Data__00024toByteArray__J(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, selfPointer: jlong) -> jbyteArray? {
+  guard let env$ = environment else {
+    fatalError("Missing JNIEnv in downcall to \(#function)")
+  }
+  assert(selfPointer != 0, "selfPointer memory address was null")
+  let selfPointerBits$ = Int(Int64(fromJNI: selfPointer, in: env$))
+  guard let selfPointer$ = UnsafeMutablePointer<Data>(bitPattern: selfPointerBits$) else {
+    fatalError("selfPointer memory address was null in call to \(#function)!")
+  }
+  return selfPointer$.pointee.withUnsafeBytes { buffer in
+    buffer.getJNIValue(in: environment)
+  }
+}
+
+#if compiler(>=6.3)
+@used
+#endif
+@_cdecl("Java_org_swift_swiftkit_core_foundation_Data__00024toByteArrayIndirectCopy__J")
+public func Java_org_swift_swiftkit_core_foundation_Data__00024toByteArrayIndirectCopy__J(
+  environment: UnsafeMutablePointer<JNIEnv?>!,
+  thisClass: jclass,
+  selfPointer: jlong
+) -> jbyteArray? {
+  guard let env$ = environment else {
+    fatalError("Missing JNIEnv in downcall to \(#function)")
+  }
+  assert(selfPointer != 0, "selfPointer memory address was null")
+  let selfPointerBits$ = Int(Int64(fromJNI: selfPointer, in: env$))
+  guard let selfPointer$ = UnsafeMutablePointer<Data>(bitPattern: selfPointerBits$) else {
+    fatalError("selfPointer memory address was null in call to \(#function)!")
+  }
+  // This is a double copy, we need to initialize the array and then copy into a JVM array in getJNIValue
+  return [UInt8](selfPointer$.pointee).getJNIValue(in: environment)
+}
diff --git a/Sources/SwiftJavaRuntimeSupport/Foundation/Date+JNI.swift b/Sources/SwiftJavaRuntimeSupport/Foundation/Date+JNI.swift
new file mode 100644
index 000000000..3c27cd7af
--- /dev/null
+++ b/Sources/SwiftJavaRuntimeSupport/Foundation/Date+JNI.swift
@@ -0,0 +1,47 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftJava
+import SwiftJavaJNICore
+
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
+@JavaImplementation("org.swift.swiftkit.core.foundation.Date")
+extension Date {
+  @JavaMethod("$init")
+  static func _init(environment: UnsafeMutablePointer<JNIEnv?>!, timeIntervalSince1970: Double) -> Int64 {
+    let result$ = UnsafeMutablePointer<Date>.allocate(capacity: 1)
+    result$.initialize(to: Date(timeIntervalSince1970: timeIntervalSince1970))
+    return Int64(Int(bitPattern: result$))
+  }
+
+  @JavaMethod("$getTimeIntervalSince1970")
+  static func _getTimeIntervalSince1970(environment: UnsafeMutablePointer<JNIEnv?>!, selfPointer: Int64) -> Double {
+    let selfPointer$ = UnsafeMutablePointer<Date>(bitPattern: Int(selfPointer))
+    guard let selfPointer$ else {
+      fatalError("selfPointer memory address was null in call to \(#function)!")
+    }
+    return selfPointer$.pointee.timeIntervalSince1970
+  }
+
+  @JavaMethod("$typeMetadataAddressDowncall")
+  static func _typeMetadataAddressDowncall(environment: UnsafeMutablePointer<JNIEnv?>!) -> Int64 {
+    let metadataPointer = unsafeBitCast(Date.self, to: UnsafeRawPointer.self)
+    return Int64(Int(bitPattern: metadataPointer))
+  }
+}
diff --git a/Sources/SwiftRuntimeFunctions/foundation/Data+FFM.swift b/Sources/SwiftRuntimeFunctions/foundation/Data+FFM.swift
new file mode 100644
index 000000000..b7e2b6ab5
--- /dev/null
+++ b/Sources/SwiftRuntimeFunctions/foundation/Data+FFM.swift
@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
+
+// ==== --------------------------------------------------
+// Thunks for Data
+
+@_cdecl("swiftjava_getType_SwiftRuntimeFunctions_Data")
+public func swiftjava_getType_SwiftRuntimeFunctions_Data() -> UnsafeMutableRawPointer /* Any.Type */ {
+  unsafeBitCast(Data.self, to: UnsafeMutableRawPointer.self)
+}
+
+@_cdecl("swiftjava_SwiftRuntimeFunctions_Data_init_bytes_count")
+public func swiftjava_SwiftRuntimeFunctions_Data_init_bytes_count(_ bytes: UnsafeRawPointer, _ count: Int, _ _result: UnsafeMutableRawPointer) {
+  _result.assumingMemoryBound(to: Data.self).initialize(to: Data(bytes: bytes, count: count))
+}
+
+@_cdecl("swiftjava_SwiftRuntimeFunctions_Data_init__")
+public func swiftjava_SwiftRuntimeFunctions_Data_init__(_ bytes_pointer: UnsafeRawPointer, _ bytes_count: Int, _ _result: UnsafeMutableRawPointer) {
+  _result.assumingMemoryBound(to: Data.self).initialize(to: Data([UInt8](UnsafeRawBufferPointer(start: bytes_pointer, count: bytes_count))))
+}
+
+@_cdecl("swiftjava_SwiftRuntimeFunctions_Data_count$get")
+public func swiftjava_SwiftRuntimeFunctions_Data_count$get(_ self: UnsafeRawPointer) -> Int {
+  self.assumingMemoryBound(to: Data.self).pointee.count
+}
+
+@_cdecl("swiftjava_SwiftRuntimeFunctions_Data_withUnsafeBytes__")
+public func swiftjava_SwiftRuntimeFunctions_Data_withUnsafeBytes__(_ body: @convention(c) (UnsafeRawPointer?, Int) -> Void, _ self: UnsafeRawPointer) {
+  self.assumingMemoryBound(to: Data.self).pointee.withUnsafeBytes({ (_0) in
+    body(_0.baseAddress, _0.count)
+  })
+}
+
+@_cdecl("swiftjava_SwiftRuntimeFunctions_Data_copyBytes__")
+public func swiftjava_SwiftRuntimeFunctions_Data_copyBytes__(
+  selfPointer: UnsafeRawPointer,
+  destinationPointer: UnsafeMutableRawPointer,
+  count: Int
+) {
+  let data = selfPointer.assumingMemoryBound(to: Data.self).pointee
+  data.withUnsafeBytes { buffer in
+    destinationPointer.copyMemory(from: buffer.baseAddress!, byteCount: count)
+  }
+}
+
+// ==== --------------------------------------------------
+// Thunks for DataProtocol
+
+@_cdecl("swiftjava_getType_SwiftRuntimeFunctions_DataProtocol")
+public func swiftjava_getType_SwiftRuntimeFunctions_DataProtocol() -> UnsafeMutableRawPointer /* Any.Type */ {
+  unsafeBitCast((any DataProtocol).self, to: UnsafeMutableRawPointer.self)
+}
diff --git a/SwiftKitCore/src/main/java/org/swift/swiftkit/core/foundation/Data.java b/SwiftKitCore/src/main/java/org/swift/swiftkit/core/foundation/Data.java
new file mode 100644
index 000000000..b4f58e69c
--- /dev/null
+++ b/SwiftKitCore/src/main/java/org/swift/swiftkit/core/foundation/Data.java
@@ -0,0 +1,186 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit.core.foundation;
+
+import org.swift.swiftkit.core.*;
+import org.swift.swiftkit.core.util.*;
+import org.swift.swiftkit.core.collections.*;
+
+import java.util.Objects;
+import java.util.concurrent.atomic.AtomicBoolean;
+import org.swift.swiftkit.core.annotations.*;
+
+public final class Data implements JNISwiftInstance, DataProtocol {
+  @SuppressWarnings("unused")
+  private static final boolean INITIALIZED_LIBS = initializeLibs();
+  static boolean initializeLibs() {
+      System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_JAVA);
+      return true;
+  }
+  /**
+  * The designated constructor of any imported Swift types.
+  *
+  * @param selfPointer  a pointer to the memory containing the value
+  * @param swiftArena   the arena this object belongs to. When the arena goes out of scope, this value is destroyed.
+  */
+  private Data(long selfPointer, SwiftArena swiftArena) {
+    SwiftObjects.requireNonZero(selfPointer, "selfPointer");
+    this.selfPointer = selfPointer;
+
+    // Only register once we have fully initialized the object since this will need the object pointer.
+    swiftArena.register(this);
+  }
+
+  /**
+   * Assume that the passed {@code long} represents a memory address of a {@link Data}.
+   * <p/>
+   * Warnings:
+   * <ul>
+   *   <li>No checks are performed about the compatibility of the pointed at memory and the actual Data types.</li>
+   *   <li>This operation does not copy, or retain, the pointed at pointer, so its lifetime must be ensured manually to be valid when wrapping.</li>
+   * </ul>
+   */
+  public static Data wrapMemoryAddressUnsafe(long selfPointer, SwiftArena swiftArena) {
+    return new Data(selfPointer, swiftArena);
+  }
+
+  public static Data wrapMemoryAddressUnsafe(long selfPointer) {
+    return new Data(selfPointer, SwiftMemoryManagement.DEFAULT_SWIFT_JAVA_AUTO_ARENA);
+  }
+  /** Pointer to the "self". */
+  private final long selfPointer;
+
+  /** Used to track additional state of the underlying object, e.g. if it was explicitly destroyed. */
+  private final AtomicBoolean $state$destroyed = new AtomicBoolean(false);
+
+  public long $memoryAddress() {
+    return this.selfPointer;
+  }
+
+  @Override
+  public AtomicBoolean $statusDestroyedFlag() {
+    return $state$destroyed;
+  }
+
+
+
+  // ==== --------------------------------------------------
+  // Data.init
+
+  /**
+   * Downcall to Swift:
+   * {@snippet lang=swift :
+   * public init(_ bytes: [UInt8])
+   * }
+   */
+  public static Data init(@Unsigned byte[] bytes, SwiftArena swiftArena) {
+    return Data.wrapMemoryAddressUnsafe(Data.$init(Objects.requireNonNull(bytes, "bytes must not be null")), swiftArena);
+  }
+  private static native long $init(byte[] bytes);
+
+
+
+  // ==== --------------------------------------------------
+  // getter:Data.count
+
+  /**
+   * Downcall to Swift:
+   * {@snippet lang=swift :
+   * public var count: Int
+   * }
+   */
+  public long getCount() {
+    return Data.$getCount(this.$memoryAddress());
+  }
+  private static native long $getCount(long selfPointer);
+
+  /**
+   * Creates a new Swift @{link Data} instance from a byte array.
+   *
+   * @param bytes The byte array to copy into the Data
+   * @param swiftArena The arena for memory management
+   * @return A new Data instance containing a copy of the bytes
+   */
+  public static Data fromByteArray(byte[] bytes, SwiftArena swiftArena) {
+    Objects.requireNonNull(bytes, "bytes cannot be null");
+    return Data.init(bytes, swiftArena);
+  }
+
+  /**
+   * Copies the contents of this Data to a new byte array.
+   *
+   * This is a relatively efficient implementation, which avoids native array copies,
+   * however it will still perform a copy of the data onto the JVM heap, so use this
+   * only when necessary.
+   *
+   * </p> When utmost performance is necessary, you may want to investigate the FFM mode
+   * of jextract which is able to map memory more efficiently.
+   *
+   * @return A byte array containing a copy of this Data's bytes
+   */
+  public byte[] toByteArray() {
+    return $toByteArray(this.$memoryAddress());
+  }
+  private static native byte[] $toByteArray(long selfPointer);
+
+  /**
+   * Copies the contents of this Data to a new byte array.
+   *
+   * @deprecated Prefer using the `toByteArray` method as it is more performant.
+   * This implementation uses a naive conversion path from native bytes into jbytes
+   * and then copying them onto the jvm heap.
+   *
+   * @return A byte array containing a copy of this Data's bytes
+   */
+  @Deprecated(forRemoval = true)
+  public byte[] toByteArrayIndirectCopy() {
+    return $toByteArrayIndirectCopy(this.$memoryAddress());
+  }
+  private static native byte[] $toByteArrayIndirectCopy(long selfPointer);
+
+  private static native long $typeMetadataAddressDowncall();
+  @Override
+  public long $typeMetadataAddress() {
+    return Data.$typeMetadataAddressDowncall();
+  }
+
+  public String toString() {
+    return SwiftObjects.toString(this.$memoryAddress(), this.$typeMetadataAddress());
+  }
+
+  public String toDebugString() {
+    return SwiftObjects.toDebugString(this.$memoryAddress(), this.$typeMetadataAddress());
+  }
+
+  @Override
+  public Runnable $createDestroyFunction() {
+    long self$ = this.$memoryAddress();
+    long selfType$ = this.$typeMetadataAddress();
+    if (CallTraces.TRACE_DOWNCALLS) {
+      CallTraces.traceDowncall("Data.$createDestroyFunction",
+          "this", this,
+          "self", self$);
+    }
+    return new Runnable() {
+      @Override
+      public void run() {
+        if (CallTraces.TRACE_DOWNCALLS) {
+          CallTraces.traceDowncall("Data.$destroy", "self", self$);
+        }
+        SwiftObjects.destroy(self$, selfType$);
+      }
+    };
+  }
+}
diff --git a/SwiftKitCore/src/main/java/org/swift/swiftkit/core/foundation/DataProtocol.java b/SwiftKitCore/src/main/java/org/swift/swiftkit/core/foundation/DataProtocol.java
new file mode 100644
index 000000000..f3240bc0d
--- /dev/null
+++ b/SwiftKitCore/src/main/java/org/swift/swiftkit/core/foundation/DataProtocol.java
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit.core.foundation;
+
+import org.swift.swiftkit.core.JNISwiftInstance;
+
+public interface DataProtocol extends JNISwiftInstance {
+}
diff --git a/SwiftKitCore/src/main/java/org/swift/swiftkit/core/foundation/Date.java b/SwiftKitCore/src/main/java/org/swift/swiftkit/core/foundation/Date.java
new file mode 100644
index 000000000..157fe4f81
--- /dev/null
+++ b/SwiftKitCore/src/main/java/org/swift/swiftkit/core/foundation/Date.java
@@ -0,0 +1,182 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit.core.foundation;
+
+import org.swift.swiftkit.core.*;
+import org.swift.swiftkit.core.util.*;
+import org.swift.swiftkit.core.collections.*;
+import java.util.Objects;
+import java.util.concurrent.atomic.AtomicBoolean;
+import org.swift.swiftkit.core.annotations.*;
+
+public final class Date implements JNISwiftInstance {
+  @SuppressWarnings("unused")
+  private static final boolean INITIALIZED_LIBS = initializeLibs();
+  static boolean initializeLibs() {
+      System.loadLibrary(SwiftLibraries.LIB_NAME_SWIFT_JAVA);
+      return true;
+  }
+  /**
+  * The designated constructor of any imported Swift types.
+  *
+  * @param selfPointer  a pointer to the memory containing the value
+  * @param swiftArena   the arena this object belongs to. When the arena goes out of scope, this value is destroyed.
+  */
+  private Date(long selfPointer, SwiftArena swiftArena) {
+    SwiftObjects.requireNonZero(selfPointer, "selfPointer");
+    this.selfPointer = selfPointer;
+
+    // Only register once we have fully initialized the object since this will need the object pointer.
+    swiftArena.register(this);
+  }
+
+  /**
+   * Assume that the passed {@code long} represents a memory address of a {@link Date}.
+   * <p/>
+   * Warnings:
+   * <ul>
+   *   <li>No checks are performed about the compatibility of the pointed at memory and the actual Date types.</li>
+   *   <li>This operation does not copy, or retain, the pointed at pointer, so its lifetime must be ensured manually to be valid when wrapping.</li>
+   * </ul>
+   */
+  public static Date wrapMemoryAddressUnsafe(long selfPointer, SwiftArena swiftArena) {
+    return new Date(selfPointer, swiftArena);
+  }
+
+  public static Date wrapMemoryAddressUnsafe(long selfPointer) {
+    return new Date(selfPointer, SwiftMemoryManagement.DEFAULT_SWIFT_JAVA_AUTO_ARENA);
+  }
+  /** Pointer to the "self". */
+  private final long selfPointer;
+
+  /** Used to track additional state of the underlying object, e.g. if it was explicitly destroyed. */
+  private final AtomicBoolean $state$destroyed = new AtomicBoolean(false);
+
+  public long $memoryAddress() {
+    return this.selfPointer;
+  }
+
+  @Override
+  public AtomicBoolean $statusDestroyedFlag() {
+    return $state$destroyed;
+  }
+
+
+  // ==== --------------------------------------------------
+  // Date.init
+
+  /**
+   * Downcall to Swift:
+   * {@snippet lang=swift :
+   * public init(timeIntervalSince1970: Double)
+   * }
+   */
+  public static Date init(double timeIntervalSince1970, SwiftArena swiftArena) {
+    return Date.wrapMemoryAddressUnsafe(Date.$init(timeIntervalSince1970), swiftArena);
+  }
+  private static native long $init(double timeIntervalSince1970);
+
+
+  // ==== --------------------------------------------------
+  // getter:Date.timeIntervalSince1970
+
+  /**
+   * Downcall to Swift:
+   * {@snippet lang=swift :
+   * public var timeIntervalSince1970: Double
+   * }
+   */
+  public double getTimeIntervalSince1970() {
+    return Date.$getTimeIntervalSince1970(this.$memoryAddress());
+  }
+  private static native double $getTimeIntervalSince1970(long selfPointer);
+
+  /**
+   * Converts this wrapped date to a Java {@link java.time.Instant}.
+   * <p>
+   * This method constructs the {@code Instant} using the underlying {@code double} value
+   * representing seconds since the Unix Epoch (January 1, 1970).
+   * </p>
+   *
+   * @return A {@code java.time.Instant} derived from the floating-point timestamp.
+   */
+  public java.time.Instant toInstant() {
+      long seconds = (long) this.getTimeIntervalSince1970();
+      long nanos = Math.round((this.getTimeIntervalSince1970() - seconds) * 1_000_000_000);
+      return java.time.Instant.ofEpochSecond(seconds, nanos);
+  }
+
+  /**
+   * Initializes a Swift {@code Foundation.Date} from a Java {@link java.time.Instant}.
+   *
+   * <h3>Warning: Precision Loss</h3>
+   * <p>
+   * <strong>The input precision will be degraded.</strong>
+   * </p>
+   * <p>
+   * Java's {@code Instant} stores time with <strong>nanosecond</strong> precision (9 decimal places).
+   * However, this class stores time as a 64-bit floating-point value.
+   * </p>
+   * <p>
+   * This leaves enough capacity for <strong>microsecond</strong> precision (approx. 6 decimal places).
+   * </p>
+   * <p>
+   * Consequently, the last ~3 digits of the {@code Instant}'s nanosecond field will be
+   * truncated or subjected to rounding errors during conversion.
+   * </p>
+   *
+   * @param instant The source timestamp to convert.
+   * @return A date derived from the input instant with microsecond precision.
+   */
+  public static Date fromInstant(java.time.Instant instant, SwiftArena swiftArena) {
+    Objects.requireNonNull(instant, "Instant cannot be null");
+    double timeIntervalSince1970 = instant.getEpochSecond() + (instant.getNano() / 1_000_000_000.0);
+    return Date.init(timeIntervalSince1970, swiftArena);
+  }
+
+  private static native long $typeMetadataAddressDowncall();
+  @Override
+  public long $typeMetadataAddress() {
+    return Date.$typeMetadataAddressDowncall();
+  }
+
+  public String toString() {
+    return SwiftObjects.toString(this.$memoryAddress(), this.$typeMetadataAddress());
+  }
+
+  public String toDebugString() {
+    return SwiftObjects.toDebugString(this.$memoryAddress(), this.$typeMetadataAddress());
+  }
+
+  @Override
+  public Runnable $createDestroyFunction() {
+    long self$ = this.$memoryAddress();
+    long selfType$ = this.$typeMetadataAddress();
+    if (CallTraces.TRACE_DOWNCALLS) {
+      CallTraces.traceDowncall("Date.$createDestroyFunction",
+          "this", this,
+          "self", self$);
+    }
+    return new Runnable() {
+      @Override
+      public void run() {
+        if (CallTraces.TRACE_DOWNCALLS) {
+          CallTraces.traceDowncall("Date.$destroy", "self", self$);
+        }
+        SwiftObjects.destroy(self$, selfType$);
+      }
+    };
+  }
+}
diff --git a/SwiftKitFFM/src/main/java/org/swift/swiftkit/ffm/foundation/Data.java b/SwiftKitFFM/src/main/java/org/swift/swiftkit/ffm/foundation/Data.java
new file mode 100644
index 000000000..ffeaea2eb
--- /dev/null
+++ b/SwiftKitFFM/src/main/java/org/swift/swiftkit/ffm/foundation/Data.java
@@ -0,0 +1,406 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit.ffm.foundation;
+
+import org.swift.swiftkit.core.*;
+import org.swift.swiftkit.core.util.*;
+import org.swift.swiftkit.ffm.*;
+import org.swift.swiftkit.ffm.generated.*;
+import org.swift.swiftkit.core.annotations.*;
+import java.lang.foreign.*;
+import java.lang.invoke.*;
+import java.util.*;
+
+public final class Data extends FFMSwiftInstance implements SwiftValue {
+  static final String LIB_NAME = "SwiftRuntimeFunctions";
+  static final Arena LIBRARY_ARENA = Arena.ofAuto();
+  @SuppressWarnings("unused")
+  private static final boolean INITIALIZED_LIBS = initializeLibs();
+  static boolean initializeLibs() {
+      SwiftLibraries.loadLibraryWithFallbacks(SwiftLibraries.LIB_NAME_SWIFT_CORE);
+      SwiftLibraries.loadLibraryWithFallbacks(SwiftLibraries.LIB_NAME_SWIFT_JAVA);
+      SwiftLibraries.loadLibraryWithFallbacks(SwiftLibraries.LIB_NAME_SWIFT_RUNTIME_FUNCTIONS);
+      SwiftLibraries.loadLibraryWithFallbacks(LIB_NAME);
+      return true;
+  }
+
+  public static final SwiftAnyType TYPE_METADATA =
+      new SwiftAnyType(SwiftRuntime.swiftjava.getType("SwiftRuntimeFunctions", "Data"));
+  public SwiftAnyType $swiftType() {
+      return TYPE_METADATA;
+  }
+
+  public static final GroupLayout $LAYOUT = (GroupLayout) SwiftValueWitnessTable.layoutOfSwiftType(TYPE_METADATA.$memorySegment());
+  public GroupLayout $layout() {
+      return $LAYOUT;
+  }
+
+  private Data(MemorySegment segment, AllocatingSwiftArena arena) {
+    super(segment, arena);
+  }
+
+  /**
+   * Assume that the passed {@code MemorySegment} represents a memory address of a {@link Data}.
+   * <p/>
+   * Warnings:
+   * <ul>
+   *   <li>No checks are performed about the compatibility of the pointed at memory and the actual Data types.</li>
+   *   <li>This operation does not copy, or retain, the pointed at pointer, so its lifetime must be ensured manually to be valid when wrapping.</li>
+   * </ul>
+   */
+  public static Data wrapMemoryAddressUnsafe(MemorySegment selfPointer, AllocatingSwiftArena arena) {
+    return new Data(selfPointer, arena);
+  }
+
+  // ==== --------------------------------------------------
+  // Data.init
+
+  /**
+   * {@snippet lang=c :
+   * void swiftjava_SwiftRuntimeFunctions_Data_init_bytes_count(const void *bytes, ptrdiff_t count, void *_result)
+   * }
+   */
+  private static class swiftjava_SwiftRuntimeFunctions_Data_init_bytes_count {
+    private static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
+      /* bytes: */SwiftValueLayout.SWIFT_POINTER,
+      /* count: */SwiftValueLayout.SWIFT_INT,
+      /* _result: */SwiftValueLayout.SWIFT_POINTER
+    );
+    private static final MemorySegment ADDR =
+            SwiftRuntime.findOrThrow("swiftjava_SwiftRuntimeFunctions_Data_init_bytes_count");
+    private static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
+    public static void call(java.lang.foreign.MemorySegment bytes, long count, java.lang.foreign.MemorySegment _result) {
+      try {
+        if (CallTraces.TRACE_DOWNCALLS) {
+          CallTraces.traceDowncall(bytes, count, _result);
+        }
+        HANDLE.invokeExact(bytes, count, _result);
+      } catch (Throwable ex$) {
+        throw new AssertionError("should not reach here", ex$);
+      }
+    }
+  }
+
+  /**
+   * Downcall to Swift:
+   * {@snippet lang=swift :
+   * public init(bytes: UnsafeRawPointer, count: Int)
+   * }
+   */
+  public static Data init(java.lang.foreign.MemorySegment bytes, long count, AllocatingSwiftArena swiftArena) throws SwiftIntegerOverflowException {
+    MemorySegment result$ = swiftArena.allocate(Data.$LAYOUT);
+    if (SwiftValueLayout.has32bitSwiftInt) {
+      if (count < Integer.MIN_VALUE || count > Integer.MAX_VALUE) {
+        throw new SwiftIntegerOverflowException("Parameter 'count' overflow: " + count);
+      }
+    }
+    swiftjava_SwiftRuntimeFunctions_Data_init_bytes_count.call(bytes, count, result$);
+    return Data.wrapMemoryAddressUnsafe(result$, swiftArena);
+  }
+
+  // ==== --------------------------------------------------
+  // Data.init
+
+  /**
+   * {@snippet lang=c :
+   * void swiftjava_SwiftRuntimeFunctions_Data_init__(const void *bytes_pointer, ptrdiff_t bytes_count, void *_result)
+   * }
+   */
+  private static class swiftjava_SwiftRuntimeFunctions_Data_init__ {
+    private static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
+      /* bytes_pointer: */SwiftValueLayout.SWIFT_POINTER,
+      /* bytes_count: */SwiftValueLayout.SWIFT_INT,
+      /* _result: */SwiftValueLayout.SWIFT_POINTER
+    );
+    private static final MemorySegment ADDR =
+      SwiftRuntime.findOrThrow("swiftjava_SwiftRuntimeFunctions_Data_init__");
+    private static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
+    public static void call(java.lang.foreign.MemorySegment bytes_pointer, long bytes_count, java.lang.foreign.MemorySegment _result) {
+      try {
+        if (CallTraces.TRACE_DOWNCALLS) {
+          CallTraces.traceDowncall(bytes_pointer, bytes_count, _result);
+        }
+        HANDLE.invokeExact(bytes_pointer, bytes_count, _result);
+      } catch (Throwable ex$) {
+        throw new AssertionError("should not reach here", ex$);
+      }
+    }
+  }
+
+  /**
+   * Downcall to Swift:
+   * {@snippet lang=swift :
+   * public init(_ bytes: [UInt8])
+   * }
+   */
+  public static Data init(@Unsigned byte[] bytes, AllocatingSwiftArena swiftArena) {
+    try(var arena$ = Arena.ofConfined()) {
+      MemorySegment result$ = swiftArena.allocate(Data.$LAYOUT);
+      swiftjava_SwiftRuntimeFunctions_Data_init__.call(arena$.allocateFrom(ValueLayout.JAVA_BYTE, bytes), bytes.length, result$);
+      return Data.wrapMemoryAddressUnsafe(result$, swiftArena);
+    }
+  }
+
+  // ==== --------------------------------------------------
+  // getter:Data.count
+
+  /**
+   * {@snippet lang=c :
+   * ptrdiff_t swiftjava_SwiftRuntimeFunctions_Data_count$get(const void *self)
+   * }
+   */
+  private static class swiftjava_SwiftRuntimeFunctions_Data_count$get {
+    private static final FunctionDescriptor DESC = FunctionDescriptor.of(
+      /* -> */SwiftValueLayout.SWIFT_INT,
+      /* self: */SwiftValueLayout.SWIFT_POINTER
+    );
+    private static final MemorySegment ADDR =
+      SwiftRuntime.findOrThrow("swiftjava_SwiftRuntimeFunctions_Data_count$get");
+    private static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
+    public static long call(java.lang.foreign.MemorySegment self) {
+      try {
+        if (CallTraces.TRACE_DOWNCALLS) {
+          CallTraces.traceDowncall(self);
+        }
+        return (long) HANDLE.invokeExact(self);
+      } catch (Throwable ex$) {
+        throw new AssertionError("should not reach here", ex$);
+      }
+    }
+  }
+
+  /**
+   * Downcall to Swift:
+   * {@snippet lang=swift :
+   * public var count: Int
+   * }
+   */
+  public long getCount() throws SwiftIntegerOverflowException {
+    $ensureAlive();
+    long result$checked = swiftjava_SwiftRuntimeFunctions_Data_count$get.call(this.$memorySegment());
+    if (SwiftValueLayout.has32bitSwiftInt) {
+      if (result$checked < Integer.MIN_VALUE || result$checked > Integer.MAX_VALUE) {
+        throw new SwiftIntegerOverflowException("Return value overflow: " + result$checked);
+      }
+    }
+    return result$checked;
+  }
+
+  // ==== --------------------------------------------------
+  // Data.withUnsafeBytes
+
+  /**
+   * {@snippet lang=c :
+   * void swiftjava_SwiftRuntimeFunctions_Data_withUnsafeBytes__(void (*body)(const void *, ptrdiff_t), const void *self)
+   * }
+   */
+  private static class swiftjava_SwiftRuntimeFunctions_Data_withUnsafeBytes__ {
+    private static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
+      /* body: */SwiftValueLayout.SWIFT_POINTER,
+      /* self: */SwiftValueLayout.SWIFT_POINTER
+    );
+    private static final MemorySegment ADDR =
+      SwiftRuntime.findOrThrow("swiftjava_SwiftRuntimeFunctions_Data_withUnsafeBytes__");
+    private static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
+    public static void call(java.lang.foreign.MemorySegment body, java.lang.foreign.MemorySegment self) {
+      try {
+        if (CallTraces.TRACE_DOWNCALLS) {
+          CallTraces.traceDowncall(body, self);
+        }
+        HANDLE.invokeExact(body, self);
+      } catch (Throwable ex$) {
+        throw new AssertionError("should not reach here", ex$);
+      }
+    }
+    /**
+     * {snippet lang=c :
+     * void (*)(const void *, ptrdiff_t)
+     * }
+     */
+    private static class $body {
+      @FunctionalInterface
+      public interface Function {
+        void apply(java.lang.foreign.MemorySegment _0, long _1);
+      }
+      private static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
+        /* _0: */SwiftValueLayout.SWIFT_POINTER,
+        /* _1: */SwiftValueLayout.SWIFT_INT
+      );
+      private static final MethodHandle HANDLE = SwiftRuntime.upcallHandle(Function.class, "apply", DESC);
+      private static MemorySegment toUpcallStub(Function fi, Arena arena) {
+        return Linker.nativeLinker().upcallStub(HANDLE.bindTo(fi), DESC, arena);
+      }
+    }
+  }
+  public static class withUnsafeBytes {
+    @FunctionalInterface
+    public interface body {
+      void apply(java.lang.foreign.MemorySegment _0);
+    }
+    private static MemorySegment $toUpcallStub(body fi, Arena arena) {
+      return swiftjava_SwiftRuntimeFunctions_Data_withUnsafeBytes__.$body.toUpcallStub((_0_pointer, _0_count) -> {
+        fi.apply(_0_pointer.reinterpret(_0_count));
+      }, arena);
+    }
+  }
+
+  /**
+   * Downcall to Swift:
+   * {@snippet lang=swift :
+   * public func withUnsafeBytes(_ body: (UnsafeRawBufferPointer) -> Void)
+   * }
+   */
+  public void withUnsafeBytes(withUnsafeBytes.body body) {
+    $ensureAlive();
+    try(var arena$ = Arena.ofConfined()) {
+      swiftjava_SwiftRuntimeFunctions_Data_withUnsafeBytes__.call(withUnsafeBytes.$toUpcallStub(body, arena$), this.$memorySegment());
+    }
+  }
+
+  // ==== --------------------------------------------------
+  // Data helper methods
+
+  /**
+   * Creates a new Swift {@link Data} instance from a byte array.
+   *
+   * @param bytes The byte array to copy into the Data
+   * @param arena The arena for memory management
+   * @return A new Data instance containing a copy of the bytes
+   */
+  public static Data fromByteArray(byte[] bytes, AllocatingSwiftArena arena) {
+    Objects.requireNonNull(bytes, "bytes cannot be null");
+    return Data.init(bytes, arena);
+  }
+
+  /**
+   * {@snippet lang=c :
+   * void swiftjava_SwiftRuntimeFunctions_Data_copyBytes__(void *const self, void *destination, ptrdiff_t count)
+   * }
+   */
+  private static class swiftjava_SwiftRuntimeFunctions_Data_copyBytes__ {
+    private static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
+      /* self: */SwiftValueLayout.SWIFT_POINTER,
+      /* destination: */SwiftValueLayout.SWIFT_POINTER,
+      /* count: */SwiftValueLayout.SWIFT_INT
+    );
+    private static final MemorySegment ADDR =
+      SwiftRuntime.findOrThrow("swiftjava_SwiftRuntimeFunctions_Data_copyBytes__");
+    private static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
+    public static void call(java.lang.foreign.MemorySegment self, java.lang.foreign.MemorySegment destination, long count) {
+      try {
+        if (CallTraces.TRACE_DOWNCALLS) {
+          CallTraces.traceDowncall(self, destination, count);
+        }
+        HANDLE.invokeExact(self, destination, count);
+      } catch (Throwable ex$) {
+        throw new AssertionError("should not reach here", ex$);
+      }
+    }
+  }
+
+  /**
+   * Copies the contents of this Data to a new {@link MemorySegment}.
+   *
+   * This is the most efficient way to access Data bytes from Java when you don't
+   * need a {@code byte[]}. The returned segment is valid for the lifetime of the arena.
+   *
+   * <p>Copy count: 1 (Swift Data -> MemorySegment)
+   *
+   * @param arena The arena to allocate the segment in
+   * @return A MemorySegment containing a copy of this Data's bytes
+   */
+  public MemorySegment toMemorySegment(AllocatingSwiftArena arena) {
+    $ensureAlive();
+    long count = getCount();
+    if (count == 0) return MemorySegment.NULL;
+    MemorySegment segment = arena.allocate(count);
+    swiftjava_SwiftRuntimeFunctions_Data_copyBytes__.call(this.$memorySegment(), segment, count);
+    return segment;
+  }
+
+  /**
+   * Copies the contents of this Data to a new {@link java.nio.ByteBuffer}.
+   *
+   * The returned {@link java.nio.ByteBuffer} is a view over native memory and is valid for the
+   * lifetime of the arena. This avoids an additional copy to the Java heap.
+   *
+   * <p>Copy count: 1 (Swift Data -> native memory (managed by passed arena), then zero-copy view)
+   *
+   * @param arena The arena to allocate the underlying memory in
+   * @return A ByteBuffer view of the copied bytes
+   */
+  public java.nio.ByteBuffer toByteBuffer(AllocatingSwiftArena arena) {
+    $ensureAlive();
+    long count = getCount();
+    if (count == 0) return java.nio.ByteBuffer.allocate(0);
+    MemorySegment segment = arena.allocate(count);
+    swiftjava_SwiftRuntimeFunctions_Data_copyBytes__.call(this.$memorySegment(), segment, count);
+    return segment.asByteBuffer();
+  }
+
+  /**
+   * Copies the contents of this Data to a new byte array.
+   * The lifetime of the array is independent of the arena, the arena is just used for an intermediary copy.
+   *
+   * <p>Copy count: 2 (Swift Data -> MemorySegment -> byte[])
+   *
+   * <p>For better performance when you can work with {@link MemorySegment} or
+   * {@link java.nio.ByteBuffer}, prefer {@link #toMemorySegment} or {@link #toByteBuffer}.
+   *
+   * @param arena The arena to use for temporary native memory allocation
+   * @return A byte array containing a copy of this Data's bytes
+   */
+  public byte[] toByteArray(AllocatingSwiftArena arena) {
+    $ensureAlive();
+    long count = getCount();
+    if (count == 0) return new byte[0];
+    MemorySegment segment = arena.allocate(count);
+    swiftjava_SwiftRuntimeFunctions_Data_copyBytes__.call(this.$memorySegment(), segment, count);
+    return segment.toArray(ValueLayout.JAVA_BYTE);
+  }
+
+  /**
+   * Copies the contents of this Data to a new byte array.
+   * The lifetime of the array is independent of the arena, the arena is just used for an intermediary copy.
+   *
+   * This is a convenience method that creates a temporary arena for the copy.
+   * For repeated calls, prefer {@link #toByteArray(AllocatingSwiftArena)} to reuse an arena.
+   *
+   * <p>Copy count: 2 (Swift Data -> MemorySegment -> byte[])
+   *
+   * <p>For better performance when you can work with {@link MemorySegment} or
+   * {@link java.nio.ByteBuffer}, prefer {@link #toMemorySegment} or {@link #toByteBuffer}.
+   *
+   * @return A byte array containing a copy of this Data's bytes
+   */
+  public byte[] toByteArray() {
+    $ensureAlive();
+    long count = getCount();
+    if (count == 0) return new byte[0];
+    try (var arena = Arena.ofConfined()) {
+      MemorySegment segment = arena.allocate(count);
+      swiftjava_SwiftRuntimeFunctions_Data_copyBytes__.call(this.$memorySegment(), segment, count);
+      return segment.toArray(ValueLayout.JAVA_BYTE);
+    }
+  }
+  @Override
+  public String toString() {
+      return getClass().getSimpleName()
+          + "("
+          + SwiftRuntime.nameOfSwiftType($swiftType().$memorySegment(), true)
+          + ")@"
+          + $memorySegment();
+  }
+}
diff --git a/SwiftKitFFM/src/main/java/org/swift/swiftkit/ffm/foundation/DataProtocol.java b/SwiftKitFFM/src/main/java/org/swift/swiftkit/ffm/foundation/DataProtocol.java
new file mode 100644
index 000000000..2881ac85e
--- /dev/null
+++ b/SwiftKitFFM/src/main/java/org/swift/swiftkit/ffm/foundation/DataProtocol.java
@@ -0,0 +1,75 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2026 Apple Inc. and the Swift.org project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+package org.swift.swiftkit.ffm.foundation;
+
+import org.swift.swiftkit.core.*;
+import org.swift.swiftkit.core.util.*;
+import org.swift.swiftkit.ffm.*;
+import org.swift.swiftkit.ffm.generated.*;
+import org.swift.swiftkit.core.annotations.*;
+import java.lang.foreign.*;
+import java.lang.invoke.*;
+import java.util.*;
+
+public final class DataProtocol extends FFMSwiftInstance implements SwiftValue {
+  static final String LIB_NAME = "SwiftRuntimeFunctions";
+  static final Arena LIBRARY_ARENA = Arena.ofAuto();
+  @SuppressWarnings("unused")
+  private static final boolean INITIALIZED_LIBS = initializeLibs();
+  static boolean initializeLibs() {
+      SwiftLibraries.loadLibraryWithFallbacks(SwiftLibraries.LIB_NAME_SWIFT_CORE);
+      SwiftLibraries.loadLibraryWithFallbacks(SwiftLibraries.LIB_NAME_SWIFT_JAVA);
+      SwiftLibraries.loadLibraryWithFallbacks(SwiftLibraries.LIB_NAME_SWIFT_RUNTIME_FUNCTIONS);
+      SwiftLibraries.loadLibraryWithFallbacks(LIB_NAME);
+      return true;
+  }
+
+  public static final SwiftAnyType TYPE_METADATA =
+      new SwiftAnyType(SwiftRuntime.swiftjava.getType("SwiftRuntimeFunctions", "DataProtocol"));
+  public SwiftAnyType $swiftType() {
+      return TYPE_METADATA;
+  }
+
+  public static final GroupLayout $LAYOUT = (GroupLayout) SwiftValueWitnessTable.layoutOfSwiftType(TYPE_METADATA.$memorySegment());
+  public GroupLayout $layout() {
+      return $LAYOUT;
+  }
+
+  private DataProtocol(MemorySegment segment, AllocatingSwiftArena arena) {
+    super(segment, arena);
+  }
+
+  /**
+   * Assume that the passed {@code MemorySegment} represents a memory address of a {@link DataProtocol}.
+   * <p/>
+   * Warnings:
+   * <ul>
+   *   <li>No checks are performed about the compatibility of the pointed at memory and the actual DataProtocol types.</li>
+   *   <li>This operation does not copy, or retain, the pointed at pointer, so its lifetime must be ensured manually to be valid when wrapping.</li>
+   * </ul>
+   */
+  public static DataProtocol wrapMemoryAddressUnsafe(MemorySegment selfPointer, AllocatingSwiftArena arena) {
+    return new DataProtocol(selfPointer, arena);
+  }
+
+  @Override
+  public String toString() {
+      return getClass().getSimpleName()
+          + "("
+          + SwiftRuntime.nameOfSwiftType($swiftType().$memorySegment(), true)
+          + ")@"
+          + $memorySegment();
+  }
+}
diff --git a/Tests/JExtractSwiftTests/DataImportTests.swift b/Tests/JExtractSwiftTests/DataImportTests.swift
index e67a3db87..42149c5ee 100644
--- a/Tests/JExtractSwiftTests/DataImportTests.swift
+++ b/Tests/JExtractSwiftTests/DataImportTests.swift
@@ -95,36 +95,6 @@ final class DataImportTests {
           _result.assumingMemoryBound(to: Data.self).initialize(to: returnData())
         }
         """,
-
-        """
-        @_cdecl("swiftjava_getType_SwiftModule_Data")
-        public func swiftjava_getType_SwiftModule_Data() -> UnsafeMutableRawPointer /* Any.Type */ {
-          return unsafeBitCast(Data.self, to: UnsafeMutableRawPointer.self)
-        }
-        """,
-
-        """
-        @_cdecl("swiftjava_SwiftModule_Data_init_bytes_count")
-        public func swiftjava_SwiftModule_Data_init_bytes_count(_ bytes: UnsafeRawPointer, _ count: Int, _ _result: UnsafeMutableRawPointer) {
-          _result.assumingMemoryBound(to: Data.self).initialize(to: Data(bytes: bytes, count: count))
-        }
-        """,
-
-        """
-        @_cdecl("swiftjava_SwiftModule_Data_count$get")
-        public func swiftjava_SwiftModule_Data_count$get(_ self: UnsafeRawPointer) -> Int {
-          return self.assumingMemoryBound(to: Data.self).pointee.count
-        }
-        """,
-
-        """
-        @_cdecl("swiftjava_SwiftModule_Data_withUnsafeBytes__")
-        public func swiftjava_SwiftModule_Data_withUnsafeBytes__(_ body: @convention(c) (UnsafeRawPointer?, Int) -> Void, _ self: UnsafeRawPointer) {
-          self.assumingMemoryBound(to: Data.self).pointee.withUnsafeBytes({ (_0) in
-            return body(_0.baseAddress, _0.count)
-          })
-        }
-        """,
       ]
     )
   }
@@ -174,7 +144,7 @@ final class DataImportTests {
          * public func receiveData(dat: Data)
          * }
          */
-        public static void receiveData(Data dat) {
+        public static void receiveData(org.swift.swiftkit.ffm.foundation.Data dat) {
           swiftjava_SwiftModule_receiveData_dat.call(dat.$memorySegment());
         }
         """,
@@ -212,178 +182,10 @@ final class DataImportTests {
          * public func returnData() -> Data
          * }
          */
-        public static Data returnData(AllocatingSwiftArena swiftArena) {
-          MemorySegment result$ = swiftArena.allocate(Data.$LAYOUT);
+        public static org.swift.swiftkit.ffm.foundation.Data returnData(AllocatingSwiftArena swiftArena) {
+          MemorySegment result$ = swiftArena.allocate(org.swift.swiftkit.ffm.foundation.Data.$LAYOUT);
           swiftjava_SwiftModule_returnData.call(result$);
-          return Data.wrapMemoryAddressUnsafe(result$, swiftArena);
-        }
-        """,
-
-        """
-        /**
-         * {@snippet lang=c :
-         * void swiftjava_SwiftModule_Data_init_bytes_count(const void *bytes, ptrdiff_t count, void *_result)
-         * }
-         */
-        private static class swiftjava_SwiftModule_Data_init_bytes_count {
-          private static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
-            /* bytes: */SwiftValueLayout.SWIFT_POINTER,
-            /* count: */SwiftValueLayout.SWIFT_INT,
-            /* _result: */SwiftValueLayout.SWIFT_POINTER
-          );
-          private static final MemorySegment ADDR =
-            SwiftModule.findOrThrow("swiftjava_SwiftModule_Data_init_bytes_count");
-          private static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
-          public static void call(java.lang.foreign.MemorySegment bytes, long count, java.lang.foreign.MemorySegment _result) {
-            try {
-              if (CallTraces.TRACE_DOWNCALLS) {
-                CallTraces.traceDowncall(bytes, count, _result);
-              }
-              HANDLE.invokeExact(bytes, count, _result);
-            } catch (Throwable ex$) {
-              throw new AssertionError("should not reach here", ex$);
-            }
-          }
-        }
-        """,
-
-        """
-        /**
-         * Downcall to Swift:
-         * {@snippet lang=swift :
-         * public init(bytes: UnsafeRawPointer, count: Int)
-         * }
-         */
-        public static Data init(java.lang.foreign.MemorySegment bytes, long count, AllocatingSwiftArena swiftArena) throws SwiftIntegerOverflowException {
-          MemorySegment result$ = swiftArena.allocate(Data.$LAYOUT);
-          if (SwiftValueLayout.has32bitSwiftInt) {
-            if (count < Integer.MIN_VALUE || count > Integer.MAX_VALUE) {
-              throw new SwiftIntegerOverflowException("Parameter 'count' overflow: " + count);
-            }
-          }
-          swiftjava_SwiftModule_Data_init_bytes_count.call(bytes, count, result$);
-          return Data.wrapMemoryAddressUnsafe(result$, swiftArena);
-        }
-        """,
-
-        """
-        /**
-         * {@snippet lang=c :
-         * ptrdiff_t swiftjava_SwiftModule_Data_count$get(const void *self)
-         * }
-         */
-        private static class swiftjava_SwiftModule_Data_count$get {
-          private static final FunctionDescriptor DESC = FunctionDescriptor.of(
-            /* -> */SwiftValueLayout.SWIFT_INT,
-            /* self: */SwiftValueLayout.SWIFT_POINTER
-          );
-          private static final MemorySegment ADDR =
-            SwiftModule.findOrThrow("swiftjava_SwiftModule_Data_count$get");
-          private static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
-          public static long call(java.lang.foreign.MemorySegment self) {
-            try {
-              if (CallTraces.TRACE_DOWNCALLS) {
-                CallTraces.traceDowncall(self);
-              }
-              return (long) HANDLE.invokeExact(self);
-            } catch (Throwable ex$) {
-              throw new AssertionError("should not reach here", ex$);
-            }
-          }
-        } 
-        """,
-
-        """
-        /**
-         * Downcall to Swift:
-         * {@snippet lang=swift :
-         * public var count: Int
-         * }
-         */
-        public long getCount() throws SwiftIntegerOverflowException {
-          $ensureAlive();
-          long result$checked = swiftjava_SwiftModule_Data_count$get.call(this.$memorySegment());
-          if (SwiftValueLayout.has32bitSwiftInt) {
-            if (result$checked < Integer.MIN_VALUE || result$checked > Integer.MAX_VALUE) {
-              throw new SwiftIntegerOverflowException("Return value overflow: " + result$checked);
-            }
-          }
-          return result$checked;
-        }
-        """,
-
-        """
-        /**
-         * {@snippet lang=c :
-         * void swiftjava_SwiftModule_Data_withUnsafeBytes__(void (*body)(const void *, ptrdiff_t), const void *self)
-         * }
-         */
-        private static class swiftjava_SwiftModule_Data_withUnsafeBytes__ {
-          private static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
-            /* body: */SwiftValueLayout.SWIFT_POINTER,
-            /* self: */SwiftValueLayout.SWIFT_POINTER
-          );
-          private static final MemorySegment ADDR =
-            SwiftModule.findOrThrow("swiftjava_SwiftModule_Data_withUnsafeBytes__");
-          private static final MethodHandle HANDLE = Linker.nativeLinker().downcallHandle(ADDR, DESC);
-          public static void call(java.lang.foreign.MemorySegment body, java.lang.foreign.MemorySegment self) {
-            try {
-              if (CallTraces.TRACE_DOWNCALLS) {
-                CallTraces.traceDowncall(body, self);
-              }
-              HANDLE.invokeExact(body, self);
-            } catch (Throwable ex$) {
-              throw new AssertionError("should not reach here", ex$);
-            }
-          }
-          /**
-           * {snippet lang=c :
-           * void (*)(const void *, ptrdiff_t)
-           * }
-           */
-          private static class $body {
-            @FunctionalInterface
-            public interface Function {
-              void apply(java.lang.foreign.MemorySegment _0, long _1);
-            }
-            private static final FunctionDescriptor DESC = FunctionDescriptor.ofVoid(
-              /* _0: */SwiftValueLayout.SWIFT_POINTER,
-              /* _1: */SwiftValueLayout.SWIFT_INT
-            );
-            private static final MethodHandle HANDLE = SwiftRuntime.upcallHandle(Function.class, "apply", DESC);
-            private static MemorySegment toUpcallStub(Function fi, Arena arena) {
-              return Linker.nativeLinker().upcallStub(HANDLE.bindTo(fi), DESC, arena);
-            }
-          }
-        }
-        """,
-
-        """
-        public static class withUnsafeBytes {
-          @FunctionalInterface
-          public interface body {
-            void apply(java.lang.foreign.MemorySegment _0);
-          }
-          private static MemorySegment $toUpcallStub(body fi, Arena arena) {
-            return swiftjava_SwiftModule_Data_withUnsafeBytes__.$body.toUpcallStub((_0_pointer, _0_count) -> {
-              fi.apply(_0_pointer.reinterpret(_0_count));
-            }, arena);
-          }
-        }
-        """,
-
-        """
-        /**
-         * Downcall to Swift:
-         * {@snippet lang=swift :
-         * public func withUnsafeBytes(_ body: (UnsafeRawBufferPointer) -> Void)
-         * }
-         */
-        public void withUnsafeBytes(withUnsafeBytes.body body) {
-          $ensureAlive();
-          try(var arena$ = Arena.ofConfined()) {
-            swiftjava_SwiftModule_Data_withUnsafeBytes__.call(withUnsafeBytes.$toUpcallStub(body, arena$), this.$memorySegment());
-          }
+          return org.swift.swiftkit.ffm.foundation.Data.wrapMemoryAddressUnsafe(result$, swiftArena);
         }
         """,
       ]
@@ -413,11 +215,6 @@ final class DataImportTests {
           receiveDataProtocol(dat: dat.assumingMemoryBound(to: Data.self).pointee, dat2: dat2?.assumingMemoryBound(to: Data.self).pointee)
         }
         """,
-
-        // Just to make sure 'Data' is imported.
-        """
-        @_cdecl("swiftjava_getType_SwiftModule_Data")
-        """,
       ]
     )
   }
@@ -470,15 +267,10 @@ final class DataImportTests {
          * public func receiveDataProtocol<T: DataProtocol>(dat: some DataProtocol, dat2: T?)
          * }
          */
-        public static void receiveDataProtocol(Data dat, Optional<Data> dat2) {
+        public static void receiveDataProtocol(org.swift.swiftkit.ffm.foundation.Data dat, java.util.Optional<org.swift.swiftkit.ffm.foundation.Data> dat2) {
           swiftjava_SwiftModule_receiveDataProtocol_dat_dat2.call(dat.$memorySegment(), SwiftRuntime.toOptionalSegmentInstance(dat2));
         }
         """,
-
-        // Just to make sure 'Data' is imported.
-        """
-        public final class Data extends FFMSwiftInstance implements SwiftValue {
-        """,
       ]
     )
   }
@@ -499,7 +291,7 @@ final class DataImportTests {
       detectChunkByInitialLines: 1,
       expectedChunks: [
         """
-        public static void acceptData(Data data) {
+        public static void acceptData(org.swift.swiftkit.core.foundation.Data data) {
           SwiftModule.$acceptData(data.$memoryAddress());
         }
         """
@@ -533,7 +325,7 @@ final class DataImportTests {
       .java,
       expectedChunks: [
         """
-        public static Data returnData(SwiftArena swiftArena) {
+        public static org.swift.swiftkit.core.foundation.Data returnData(SwiftArena swiftArena) {
         """
       ]
     )
@@ -551,33 +343,6 @@ final class DataImportTests {
     )
   }
 
-  @Test("Import Data: JNI Data class")
-  func data_jni_class() throws {
-    let text = """
-      import Foundation
-      public func f() -> Data
-      """
-
-    try assertOutput(
-      input: text,
-      .jni,
-      .java,
-      detectChunkByInitialLines: 1,
-      expectedChunks: [
-        "public final class Data implements JNISwiftInstance, DataProtocol {",
-        "public long getCount() {",
-
-        "public static Data fromByteArray(byte[] bytes, SwiftArena swiftArena) {",
-
-        "public byte[] toByteArray() {",
-        "private static native byte[] $toByteArray(long selfPointer);",
-
-        "public byte[] toByteArrayIndirectCopy() {",
-        "private static native byte[] $toByteArrayIndirectCopy(long selfPointer);",
-      ]
-    )
-  }
-
   // ==== -----------------------------------------------------------------------
   // MARK: JNI DataProtocol generic parameter
 
@@ -599,7 +364,7 @@ final class DataImportTests {
       detectChunkByInitialLines: 2,
       expectedChunks: [
         """
-        public static <D extends DataProtocol> MyResult processData(D data, SwiftArena swiftArena) {
+        public static <D extends org.swift.swiftkit.core.foundation.DataProtocol> MyResult processData(D data, SwiftArena swiftArena) {
         """
       ]
     )
@@ -620,7 +385,7 @@ final class DataImportTests {
       detectChunkByInitialLines: 2,
       expectedChunks: [
         """
-        public static <D1 extends DataProtocol, D2 extends DataProtocol> boolean verify(D1 first, D2 second) {
+        public static <D1 extends org.swift.swiftkit.core.foundation.DataProtocol, D2 extends org.swift.swiftkit.core.foundation.DataProtocol> boolean verify(D1 first, D2 second) {
         """
       ]
     )
diff --git a/Tests/JExtractSwiftTests/DateTests.swift b/Tests/JExtractSwiftTests/DateTests.swift
index bf5e9ef8e..7e694640c 100644
--- a/Tests/JExtractSwiftTests/DateTests.swift
+++ b/Tests/JExtractSwiftTests/DateTests.swift
@@ -17,34 +17,8 @@ import SwiftJavaConfigurationShared
 import Testing
 
 struct DateTests {
-  @Test(
-    "Import: accept Date",
-    arguments: [
-      (
-        JExtractGenerationMode.jni,
-        /* expected Java chunks */
-        [
-          """
-          public static void acceptDate(Date date) {
-            SwiftModule.$acceptDate(date.$memoryAddress());
-          }
-          """
-        ],
-        /* expected Swift chunks */
-        [
-          """
-          @_cdecl("Java_com_example_swift_SwiftModule__00024acceptDate__J")
-          public func Java_com_example_swift_SwiftModule__00024acceptDate__J(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, date: jlong) {
-          """
-        ],
-      )
-    ]
-  )
-  func func_accept_date(
-    mode: JExtractGenerationMode,
-    expectedJavaChunks: [String],
-    expectedSwiftChunks: [String]
-  ) throws {
+  @Test("Import: accept Date")
+  func func_accept_date() throws {
     let text =
       """
       import Foundation
@@ -54,47 +28,34 @@ struct DateTests {
 
     try assertOutput(
       input: text,
-      mode,
+      .jni,
       .java,
       detectChunkByInitialLines: 1,
-      expectedChunks: expectedJavaChunks
+      expectedChunks: [
+        """
+        public static void acceptDate(org.swift.swiftkit.core.foundation.Date date) {
+          SwiftModule.$acceptDate(date.$memoryAddress());
+        }
+        """
+      ]
     )
 
     try assertOutput(
       input: text,
-      mode,
+      .jni,
       .swift,
       detectChunkByInitialLines: 1,
-      expectedChunks: expectedSwiftChunks
+      expectedChunks: [
+        """
+        @_cdecl("Java_com_example_swift_SwiftModule__00024acceptDate__J")
+        public func Java_com_example_swift_SwiftModule__00024acceptDate__J(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, date: jlong) {
+        """
+      ]
     )
   }
 
-  @Test(
-    "Import: return Date",
-    arguments: [
-      (
-        JExtractGenerationMode.jni,
-        /* expected Java chunks */
-        [
-          """
-          public static Date returnDate(SwiftArena swiftArena) {
-          """
-        ],
-        /* expected Swift chunks */
-        [
-          """
-          @_cdecl("Java_com_example_swift_SwiftModule__00024returnDate__")
-          public func Java_com_example_swift_SwiftModule__00024returnDate__(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass) -> jlong {
-          """
-        ]
-      )
-    ]
-  )
-  func func_return_Date(
-    mode: JExtractGenerationMode,
-    expectedJavaChunks: [String],
-    expectedSwiftChunks: [String]
-  ) throws {
+  @Test("Import: return Date")
+  func func_return_Date() throws {
     let text =
       """
       import Foundation
@@ -103,75 +64,25 @@ struct DateTests {
 
     try assertOutput(
       input: text,
-      mode,
+      .jni,
       .java,
-      expectedChunks: expectedJavaChunks
+      expectedChunks: [
+        """
+        public static org.swift.swiftkit.core.foundation.Date returnDate(SwiftArena swiftArena) {
+        """
+      ],
     )
 
     try assertOutput(
       input: text,
-      mode,
+      .jni,
       .swift,
-      expectedChunks: expectedSwiftChunks
-    )
-  }
-
-  @Test(
-    "Import: Date type",
-    arguments: [
-      (
-        JExtractGenerationMode.jni,
-        /* expected Java chunks */
-        [
-          """
-          public final class Date implements JNISwiftInstance {
-          """,
-          """
-          public static Date init(double timeIntervalSince1970, SwiftArena swiftArena) {
-          """,
-          """
-          public double getTimeIntervalSince1970() {
-          """,
-          """
-          public static Date fromInstant(java.time.Instant instant, SwiftArena swiftArena) {
-          """,
-          """
-          public java.time.Instant toInstant() {
-          """,
-        ],
-        /* expected Swift chunks */
-        [
-          """
-          @_cdecl("Java_com_example_swift_Date__00024init__D")
-          public func Java_com_example_swift_Date__00024init__D(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, timeIntervalSince1970: jdouble) -> jlong {
-          """,
-          """
-          @_cdecl("Java_com_example_swift_Date__00024getTimeIntervalSince1970__J")
-          public func Java_com_example_swift_Date__00024getTimeIntervalSince1970__J(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass, selfPointer: jlong) -> jdouble {
-          """,
-        ]
-      )
-    ]
-  )
-  func date_class(mode: JExtractGenerationMode, expectedJavaChunks: [String], expectedSwiftChunks: [String]) throws {
-    let text =
-      """
-      import Foundation
-      public func f() -> Date
-      """
-
-    try assertOutput(
-      input: text,
-      mode,
-      .java,
-      expectedChunks: expectedJavaChunks
-    )
-
-    try assertOutput(
-      input: text,
-      mode,
-      .swift,
-      expectedChunks: expectedSwiftChunks
+      expectedChunks: [
+        """
+        @_cdecl("Java_com_example_swift_SwiftModule__00024returnDate__")
+        public func Java_com_example_swift_SwiftModule__00024returnDate__(environment: UnsafeMutablePointer<JNIEnv?>!, thisClass: jclass) -> jlong {
+        """
+      ]
     )
   }
 }
diff --git a/Tests/JExtractSwiftTests/JNI/JNIDictionaryTest.swift b/Tests/JExtractSwiftTests/JNI/JNIDictionaryTest.swift
index 0690ee01d..ebb8ed163 100644
--- a/Tests/JExtractSwiftTests/JNI/JNIDictionaryTest.swift
+++ b/Tests/JExtractSwiftTests/JNI/JNIDictionaryTest.swift
@@ -28,7 +28,7 @@ struct JNIDictionaryTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.String, java.lang.Long> f(SwiftArena swiftArena) {
-          return SwiftDictionaryMap.<java.lang.String, java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftDictionaryMap.<java.lang.String, java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
         }
         """,
         """
@@ -104,7 +104,7 @@ struct JNIDictionaryTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.String, java.lang.Long> f(org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.String, java.lang.Long> dict, SwiftArena swiftArena) {
-          return SwiftDictionaryMap.<java.lang.String, java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(dict, "dict must not be null").$memoryAddress()), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftDictionaryMap.<java.lang.String, java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(dict, "dict must not be null").$memoryAddress()), swiftArena);
         }
         """,
         """
@@ -142,7 +142,7 @@ struct JNIDictionaryTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.String, java.lang.Long> f(org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.String, java.lang.Long> dict, SwiftArena swiftArena) {
-          return SwiftDictionaryMap.<java.lang.String, java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(dict, "dict must not be null").$memoryAddress()), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftDictionaryMap.<java.lang.String, java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(dict, "dict must not be null").$memoryAddress()), swiftArena);
         }
         """,
         """
@@ -183,7 +183,7 @@ struct JNIDictionaryTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.String, java.lang.Boolean> f(SwiftArena swiftArena) {
-          return SwiftDictionaryMap.<java.lang.String, java.lang.Boolean>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftDictionaryMap.<java.lang.String, java.lang.Boolean>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
         }
         """
       ]
@@ -200,7 +200,7 @@ struct JNIDictionaryTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.String, java.lang.Double> f(SwiftArena swiftArena) {
-          return SwiftDictionaryMap.<java.lang.String, java.lang.Double>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftDictionaryMap.<java.lang.String, java.lang.Double>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
         }
         """
       ]
@@ -217,7 +217,7 @@ struct JNIDictionaryTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.Long, java.lang.String> f(SwiftArena swiftArena) {
-          return SwiftDictionaryMap.<java.lang.Long, java.lang.String>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftDictionaryMap.<java.lang.Long, java.lang.String>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
         }
         """
       ]
@@ -234,7 +234,7 @@ struct JNIDictionaryTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.Integer, java.lang.Float> f(SwiftArena swiftArena) {
-          return SwiftDictionaryMap.<java.lang.Integer, java.lang.Float>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftDictionaryMap.<java.lang.Integer, java.lang.Float>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
         }
         """
       ]
@@ -295,7 +295,7 @@ struct JNIDictionaryTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.String, java.lang.Long> f(org.swift.swiftkit.core.collections.SwiftDictionaryMap<java.lang.String, java.lang.Long> dict, java.lang.String key, long value, SwiftArena swiftArena) {
-          return SwiftDictionaryMap.<java.lang.String, java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(dict, "dict must not be null").$memoryAddress(), key, value), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftDictionaryMap.<java.lang.String, java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(dict, "dict must not be null").$memoryAddress(), key, value), swiftArena);
         }
         """,
         """
diff --git a/Tests/JExtractSwiftTests/JNI/JNIEnumTests.swift b/Tests/JExtractSwiftTests/JNI/JNIEnumTests.swift
index e09c215ca..0f3db0ca0 100644
--- a/Tests/JExtractSwiftTests/JNI/JNIEnumTests.swift
+++ b/Tests/JExtractSwiftTests/JNI/JNIEnumTests.swift
@@ -268,7 +268,7 @@ struct JNIEnumTests {
       detectChunkByInitialLines: 1,
       expectedChunks: [
         """
-        public Optional<First> getAsFirst() {
+        public java.util.Optional<First> getAsFirst() {
           if (getDiscriminator() != Discriminator.FIRST) {
             return Optional.empty();
           }
@@ -276,7 +276,7 @@ struct JNIEnumTests {
         }
         """,
         """
-        public Optional<Second> getAsSecond() {
+        public java.util.Optional<Second> getAsSecond() {
           if (getDiscriminator() != Discriminator.SECOND) {
             return Optional.empty();
           }
@@ -285,7 +285,7 @@ struct JNIEnumTests {
         }
         """,
         """
-        public Optional<Third> getAsThird() {
+        public java.util.Optional<Third> getAsThird() {
           if (getDiscriminator() != Discriminator.THIRD) {
             return Optional.empty();
           }
diff --git a/Tests/JExtractSwiftTests/JNI/JNIGenericCombinationTests.swift b/Tests/JExtractSwiftTests/JNI/JNIGenericCombinationTests.swift
index 57651e1e1..45b4cb2ec 100644
--- a/Tests/JExtractSwiftTests/JNI/JNIGenericCombinationTests.swift
+++ b/Tests/JExtractSwiftTests/JNI/JNIGenericCombinationTests.swift
@@ -55,7 +55,7 @@ struct JNIGenericCombinationTests {
         detectChunkByInitialLines: 2,
         expectedChunks: [
           """
-          public static Optional<MyID<java.lang.String>> makeStringIDOptional(java.lang.String value, SwiftArena swiftArena) {
+          public static java.util.Optional<MyID<java.lang.String>> makeStringIDOptional(java.lang.String value, SwiftArena swiftArena) {
             byte[] result$_discriminator$ = new byte[1];
             org.swift.swiftkit.core._OutSwiftGenericInstance resultWrapped$ = new org.swift.swiftkit.core._OutSwiftGenericInstance();
             SwiftModule.$makeStringIDOptional(value, result$_discriminator$, resultWrapped$);
@@ -113,7 +113,7 @@ struct JNIGenericCombinationTests {
         detectChunkByInitialLines: 2,
         expectedChunks: [
           """
-          public static void takeStringIDOptional(Optional<MyID<java.lang.String>> value) {
+          public static void takeStringIDOptional(java.util.Optional<MyID<java.lang.String>> value) {
             SwiftModule.$takeStringIDOptional(value.map(MyID<java.lang.String>::$memoryAddress).orElse(0L));
           }
           """,
diff --git a/Tests/JExtractSwiftTests/JNI/JNIOptionalTests.swift b/Tests/JExtractSwiftTests/JNI/JNIOptionalTests.swift
index 728165bf8..d01c4b103 100644
--- a/Tests/JExtractSwiftTests/JNI/JNIOptionalTests.swift
+++ b/Tests/JExtractSwiftTests/JNI/JNIOptionalTests.swift
@@ -155,7 +155,7 @@ struct JNIOptionalTests {
          * public func optionalClass(_ arg: MyClass?) -> MyClass?
          * }
          */
-        public static Optional<MyClass> optionalClass(Optional<MyClass> arg, SwiftArena swiftArena) {
+        public static java.util.Optional<MyClass> optionalClass(java.util.Optional<MyClass> arg, SwiftArena swiftArena) {
           byte[] result$_discriminator$ = new byte[1];
           long result$ = SwiftModule.$optionalClass(arg.map(MyClass::$memoryAddress).orElse(0L), result$_discriminator$);
           return (result$_discriminator$[0] == 1) ? Optional.of(MyClass.wrapMemoryAddressUnsafe(result$, swiftArena)) : Optional.empty();
diff --git a/Tests/JExtractSwiftTests/JNI/JNISetTest.swift b/Tests/JExtractSwiftTests/JNI/JNISetTest.swift
index e654344d2..8adec8d58 100644
--- a/Tests/JExtractSwiftTests/JNI/JNISetTest.swift
+++ b/Tests/JExtractSwiftTests/JNI/JNISetTest.swift
@@ -28,7 +28,7 @@ struct JNISetTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftSet<java.lang.String> f(SwiftArena swiftArena) {
-          return SwiftSet.<java.lang.String>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftSet.<java.lang.String>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
         }
         """,
         """
@@ -104,7 +104,7 @@ struct JNISetTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftSet<java.lang.String> f(org.swift.swiftkit.core.collections.SwiftSet<java.lang.String> set, SwiftArena swiftArena) {
-          return SwiftSet.<java.lang.String>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(set, "set must not be null").$memoryAddress()), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftSet.<java.lang.String>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(set, "set must not be null").$memoryAddress()), swiftArena);
         }
         """,
         """
@@ -145,7 +145,7 @@ struct JNISetTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftSet<java.lang.Long> f(SwiftArena swiftArena) {
-          return SwiftSet.<java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftSet.<java.lang.Long>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
         }
         """
       ]
@@ -162,7 +162,7 @@ struct JNISetTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftSet<java.lang.Boolean> f(SwiftArena swiftArena) {
-          return SwiftSet.<java.lang.Boolean>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftSet.<java.lang.Boolean>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
         }
         """
       ]
@@ -179,7 +179,7 @@ struct JNISetTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftSet<java.lang.Double> f(SwiftArena swiftArena) {
-          return SwiftSet.<java.lang.Double>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftSet.<java.lang.Double>wrapMemoryAddressUnsafe(SwiftModule.$f(), swiftArena);
         }
         """
       ]
@@ -240,7 +240,7 @@ struct JNISetTest {
       expectedChunks: [
         """
         public static org.swift.swiftkit.core.collections.SwiftSet<java.lang.String> f(org.swift.swiftkit.core.collections.SwiftSet<java.lang.String> set, java.lang.String element, SwiftArena swiftArena) {
-          return SwiftSet.<java.lang.String>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(set, "set must not be null").$memoryAddress(), element), swiftArena);
+          return org.swift.swiftkit.core.collections.SwiftSet.<java.lang.String>wrapMemoryAddressUnsafe(SwiftModule.$f(Objects.requireNonNull(set, "set must not be null").$memoryAddress(), element), swiftArena);
         }
         """,
         """
diff --git a/Tests/JExtractSwiftTests/OptionalImportTests.swift b/Tests/JExtractSwiftTests/OptionalImportTests.swift
index fc169fe53..60473bd3a 100644
--- a/Tests/JExtractSwiftTests/OptionalImportTests.swift
+++ b/Tests/JExtractSwiftTests/OptionalImportTests.swift
@@ -146,7 +146,7 @@ final class OptionalImportTests {
          * public func receiveOptionalDataProto(_ arg: (some DataProtocol)?)
          * }
          */
-        public static void receiveOptionalDataProto(Optional<Data> arg) {
+        public static void receiveOptionalDataProto(java.util.Optional<org.swift.swiftkit.ffm.foundation.Data> arg) {
           swiftjava_SwiftModule_receiveOptionalDataProto__.call(SwiftRuntime.toOptionalSegmentInstance(arg));
         }
         """,
diff --git a/Tests/JExtractSwiftTests/SwiftSymbolTableTests.swift b/Tests/JExtractSwiftTests/SwiftSymbolTableTests.swift
index bdf00de18..a2b1fc9e3 100644
--- a/Tests/JExtractSwiftTests/SwiftSymbolTableTests.swift
+++ b/Tests/JExtractSwiftTests/SwiftSymbolTableTests.swift
@@ -52,8 +52,8 @@ struct SwiftSymbolTableSuite {
     #expect(symbolTable.lookupType("Z", parent: nil) == nil)
   }
 
-  @Test(arguments: [JExtractGenerationMode.jni, .ffm])
-  func resolveSelfModuleName(mode: JExtractGenerationMode) throws {
+  @Test
+  func resolveSelfModuleName() throws {
     try assertOutput(
       input: """
         import Foundation
@@ -62,13 +62,13 @@ struct SwiftSymbolTableSuite {
         public func fullyQualifiedType() -> MyModule.MyValue
         public func fullyQualifiedType2() -> Foundation.Data
         """,
-      mode,
+      .jni,
       .java,
       swiftModuleName: "MyModule",
       detectChunkByInitialLines: 1,
       expectedChunks: [
         "public static MyValue fullyQualifiedType(",
-        "public static Data fullyQualifiedType2(",
+        "public static org.swift.swiftkit.core.foundation.Data fullyQualifiedType2(",
       ],
     )
   }