Add support for DSpace 8 metadata

[jazairi]

Why these changes are being introduced:

The DSpace 8 REST API has updated metadata formatting requirements which will require updates to ETD.

Relevant ticket(s):

• ETD-685

How this addresses that need:

• Adds a new Flipflop feature flag, dspace_v8_metadata, defaulting to DSPACE_V8_METADATA=false in features.rb. When enabled, the feature serializes metadata in the new format.
• Refactors metadata construction in dspace_metadata.rb to use explicit metadata entries for clearer serialization.

Side effects of this change:

Setting the default behavior to v6 will require some cleanup once we fully launch DSpace 8. This seemed like a reasonable tradeoff, given that we are still using v6.

Developer

• All new ENV is documented in README
• All new ENV has been added to Heroku Pipeline, Staging and Prod
• ANDI or Wave has been run in accordance to
  our guide and
  all issues introduced by these changes have been resolved or opened as new
  issues (link to those issues in the Pull Request details above)
• Stakeholder approval has been confirmed (or is not needed)

Code Reviewer

• The commit message is clear and follows our guidelines
  (not just this pull request message)
• There are appropriate tests covering any new functionality
• The documentation has been updated or is unnecessary
• The changes have been verified
• New dependencies are appropriate or there were no changes

Requires database migrations?

NO

Includes new or updated dependencies?

NO

[coveralls]

coverage: 98.35% (+0.01%) from 98.338%
when pulling 6889c88 on etd-685
into e6bf8c9 on main.

[Copilot]

Pull request overview

This PR adds a feature-flagged switch to support the DSpace 8 REST API metadata payload format while preserving the existing DSpace 6 “metadata array” serialization as the default behavior.

Changes:

• Added a Flipflop feature flag (dspace_v8_metadata) driven by DSPACE_V8_METADATA.
• Refactored DspaceMetadata to build metadata as explicit entries and serialize to either DSpace 6 or DSpace 8 formats based on the flag.
• Added test coverage for both serialization formats and documented the new ENV var.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
app/models/dspace_metadata.rb	Refactors metadata construction and adds conditional serialization for DSpace 6 vs DSpace 8.
config/features.rb	Introduces dspace_v8_metadata Flipflop feature defaulted from DSPACE_V8_METADATA.
test/models/dspace_metadata_test.rb	Adds tests verifying both serialization formats and ensures existing tests run with the flag off.
app.json	Adds DSPACE_V8_METADATA to Heroku app env defaults.
README.md	Documents the new DSPACE_V8_METADATA environment variable.

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[Copilot]

ENV.fetch returns strings, so when DSPACE_V8_METADATA is set to "false" (as in app.json) the feature default becomes the string "false" rather than a boolean. To avoid the flag being interpreted incorrectly, cast this ENV value to a boolean (e.g., via ActiveModel::Type::Boolean.new.cast(...)) before passing it as the Flipflop default: (and consider doing the same for MAINTENANCE_MODE for consistency).

Suggested change

	default: ENV.fetch('MAINTENANCE_MODE', false),
	description: "Put application in maintenance mode, disabling file transfer uploads."
	feature :dspace_v8_metadata,
	default: ENV.fetch('DSPACE_V8_METADATA', false),
	default: ActiveModel::Type::Boolean.new.cast(ENV.fetch('MAINTENANCE_MODE', false)),
	description: "Put application in maintenance mode, disabling file transfer uploads."
	feature :dspace_v8_metadata,
	default: ActiveModel::Type::Boolean.new.cast(ENV.fetch('DSPACE_V8_METADATA', false)),

[jazairi]

This is a good reminder that booleans don't work in FlipFlop...but, I'm not sure casting the value as a boolean would, either? I'll have to test this out.

[JPrevost]

FWIW I'm sort of fine either way. The way you had it is how everything else in the app probably already works so it's arguably better to not "fix" it if the outcome is different behavior than elsewhere.

[Copilot]

The new DSPACE_V8_METADATA documentation is split across two lines, and the second line starts with lowercase "set" which reads like a sentence fragment in the rendered README. Consider combining into one bullet/paragraph and capitalizing "Set" to keep the ENV list formatting consistent.

Suggested change

	`DSPACE_V8_METADATA` - Toggle metadata format for publication payloads. Set to `true` for DSpace 8 format.
	set to `false` for DSpace 6 `metadata` array format. Default is `false`.
	`DSPACE_V8_METADATA` - Toggle metadata format for publication payloads. Set to `true` for DSpace 8 format, set to `false` for DSpace 6 `metadata` array format. Default is `false`.

[JPrevost]

I added a comment about some method documentation I think would help, but this looks good.

[JPrevost]

Would you mind adding comments to serialize_dspace8 and serialize_dspace6 explaining the different formats. When we ultimately refactor to only serialize_dspace8 I'd like to keep the explanation of what is going on as the data model is very odd (to me) and it feels like some docs here explaining the intent and maybe even showing a simple example would go a long way to help us remember wtf is going on in the future.