fix(workflow-compiling-service): LogicalLink OperatorIdentity round-trip

[wwong0]

What changes were proposed in this PR?

Bug fix: LogicalLink @JsonCreator constructor (amber and workflow-compiling-service)

@JsonCreator was previously placed on the String convenience constructor of LogicalLink in both modules. OperatorIdentity is a case class that Jackson serializes as an object ({"id":"op-A"}), not a plain string. When reading back a serialized LogicalLink, Jackson dispatched to the @JsonCreator String constructor but could not coerce the {"id":"op-A"} object node to a String, causing any writeValueAsString → readValue round-trip to fail with MismatchedInputException.

The fix introduces a private readOperatorIdentity(node: JsonNode, fieldName: String) helper in the companion object and moves @JsonCreator to a new JsonNode constructor that delegates to it. The helper accepts both the plain-string shape (front-end input) and the object shape (serialized form), maps null/absent ids to OperatorIdentity(null), and rejects malformed nodes. The String convenience constructor is retained but no longer carries @JsonCreator.

Any related issues, documentation, discussions?

Closes #5042
This PR continues and adopts work from #5175

How was this PR tested?

The new workflow-compiling-service LogicalLinkSpec adds unit coverage of LogicalLink and readOperatorIdentity model-level logic that existing tests do not cover and pins the leniency contract (no require guards in the compiler-service variant).

The existing amber LogicalLinkSpec was updated to match the renamed constructor section, drop the now-invalid MismatchedInputException expectation, and add a passing round-trip test.

Run with:

sbt "WorkflowExecutionService/testOnly *LogicalLinkSpec"

Result: 18/18 tests pass

sbt "WorkflowCompilingService/testOnly *LogicalLinkSpec"

Result: 15/15 tests pass

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Sonnet 4.6

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