Summary

• Optional record fields: GraphqlDecoder now properly returns Optional.empty() instead of null for Optional-typed record fields. The decoder manually constructs records with Optional fields to avoid Jackson's convertValue limitation, recursively handling N-level deep nested records.
• Non-nullable list return types: Collection/array return types never return null — the decoder returns empty collections for null body, null operation data, and any other null-producing code path.

Test plan

• Added test: decodesRecordWithOptionalFieldPresent
• Added test: decodesRecordWithOptionalFieldNull — verifies Optional.empty() not null
• Added test: decodesRecordWithOptionalFieldMissing — verifies Optional.empty() not null
• Added test: decodesNestedRecordWithOptionalFields — 2-level deep
• Added test: decodesDeeplyNestedRecordWithOptionalFields — 3-level deep
• Added test: returnsEmptyListForNullBody
• Added test: returnsEmptyListForNullOperationDataWithListType
• All 45 graphql module tests pass

🤖 Generated with Claude Code