client: shared response types across operations (useSharedResponseTypes opt-in)

[devin-ai-integration]

📝 Description

Implements cross-operation type reuse for GraphQL response types, controlled by a new useSharedResponseTypes configuration parameter (default: false). This feature reduces duplicate type generation when multiple GraphQL operations select the same fields from the same GraphQL type.

Current behavior (default): Each operation generates response types in its own package (e.g., com.example.generated.operation1.User, com.example.generated.operation2.User)

New behavior (when enabled): Response types with identical selection sets are shared across operations in a .responses package with numbered variants for different selection sets (e.g., ComplexObject, ComplexObject2, ComplexObject3)

Key implementation changes:

• Added useSharedResponseTypes: Boolean config parameter across client generator, Gradle plugin, and Maven plugin
• Introduced global caches (sharedResponseTypeSpecs, globalClassNameCache, globalTypeToSelectionSetMap) in GraphQLClientGenerator that are conditionally passed to GraphQLClientGeneratorContext
• Modified generateClassName() to route object types to .responses package when flag is enabled
• Updated type storage logic in generateTypeName.kt to conditionally store in shared vs per-operation caches
• Modified GraphQLClientGenerator.generate() to skip writing shared types in per-operation loop and instead write them once as shared types

Test coverage:

• Added integration test with two operations containing identical selection sets
• Verified generation of exactly 3 shared ComplexObject variants (ComplexObject, ComplexObject2, ComplexObject3) in .responses package

Backwards compatibility:

• Feature is opt-in (defaults to false)
• All existing tests pass
• No breaking changes to existing behavior

🔗 Related Issues

• Link to Devin run: https://app.devin.ai/sessions/2dc6c0f9c1ce4a53afad28f60917c68d
• Requested by: @arthurkkp-cog

🔍 Reviewer Checklist

• Verify all conditional logic paths in generateTypeName.kt correctly handle useSharedResponseTypes flag
• Confirm global cache initialization and lifecycle are correct in GraphQLClientGenerator
• Review package naming consistency (.responses follows pattern of .inputs, .enums)
• Verify backwards compatibility - default behavior unchanged when flag is false
• Consider whether test coverage is sufficient (currently one integration test for happy path)
• Check handling of edge cases: polymorphic types (interfaces/unions), deeply nested objects

[devin-ai-integration]

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