Fix isUnchangedStructure always returning false

[fh-ms]

Summary

• PersistenceLegacyTypeMappingResult.isUnchangedStructure compared mapping.get(legacyMember) — a Similarity<PersistenceTypeDefinitionMember> — directly against currentMember via !=. The two are unrelated types, so the check was always true and the method always returned false on the first iteration.
• The unchanged-structure fast path in PersistenceLegacyTypeHandlerCreator therefore never fired: every legacy handler went through the translating path even when the persisted layout was actually unchanged, producing more expensive handlers than necessary on load.
• Fix: extract targetElement() from the similarity (with a null guard) before comparing — same pattern already used in PersistenceLegacyTypeHandlerCreator.deriveEnumOrdinalMapping.

[Copilot]

Pull request overview

Fixes the unchanged-structure detection used during legacy type-handler creation so that persisted layouts that haven’t changed can take the fast path instead of always falling back to translating handlers.

Changes:

• Fix PersistenceLegacyTypeMappingResult.isUnchangedStructure(...) to compare the mapped target member (Similarity.targetElement()) rather than comparing a Similarity instance to a member.
• Add a null-guard for missing mappings before comparing the mapped target member.

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[Copilot]

Pull request overview

Fixes unchanged-structure detection in legacy type mapping so the legacy handler creator can take the “structure unchanged” fast path instead of always producing translating/wrapping handlers.

Changes:

• Fix isUnchangedStructure to compare Similarity.targetElement() (with null guard) against the corresponding current member.
• Make type-name comparison null-safe and add a primitive-definition special-case comparison.

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[Copilot]

Pull request overview

Fixes a logic error in PersistenceLegacyTypeMappingResult.isUnchangedStructure that prevented the “unchanged-structure” optimization from ever triggering, causing legacy type handler creation to always take the translating path.

Changes:

• Compare a legacy member’s mapping against the corresponding current member by extracting Similarity.targetElement() (with a null guard).
• Replace the old per-member compatibility check (typeName equality) with equalsStructure(...).

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[Copilot]

Pull request overview

Fixes legacy “unchanged structure” detection so the legacy-handler creation can take the fast path when the persisted member layout truly matches the current layout (e.g., renames without layout changes), avoiding unnecessary translating handlers.

Changes:

• Fix PersistenceLegacyTypeMappingResult.isUnchangedStructure(...) to compare against Similarity.targetElement() (with null guard) and to validate member compatibility via equalsLayout(...) instead of the previous always-false check.
• Introduce equalsLayout(...) / equalLayout(...) / equalLayouts(...) on PersistenceTypeDescriptionMember to compare persistent layout while ignoring member simple names.
• Add/override equalsLayout(...) for specific member kinds where layout equality needs specialized logic (primitive definitions, enum constants, complex/variable-length generic members).

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
persistence/persistence/src/main/java/org/eclipse/serializer/persistence/types/PersistenceTypeDescriptionMemberPrimitiveDefinition.java	Defines layout equality for primitive-definition members based on primitiveDefinition().
persistence/persistence/src/main/java/org/eclipse/serializer/persistence/types/PersistenceTypeDescriptionMemberFieldGenericVariableLength.java	Adds layout equality specialization for variable-length generic members.
persistence/persistence/src/main/java/org/eclipse/serializer/persistence/types/PersistenceTypeDescriptionMemberFieldGenericComplex.java	Adds deep layout equality for complex generic members (nested members compared by layout).
persistence/persistence/src/main/java/org/eclipse/serializer/persistence/types/PersistenceTypeDescriptionMemberEnumConstant.java	Adds layout equality for enum-constant entries (layout footprint is zero).
persistence/persistence/src/main/java/org/eclipse/serializer/persistence/types/PersistenceTypeDescriptionMember.java	Adds equalsLayout plus null-safe/static helpers to compare layout (and sequences by layout).
persistence/persistence/src/main/java/org/eclipse/serializer/persistence/types/PersistenceLegacyTypeMappingResult.java	Fixes unchanged-structure check to use Similarity.targetElement() and equalsLayout(...).

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