add unit test coverage for core/executor reflection layer #4833

Add coverage for the four classes/traits in common/workflow-core/.../core/executor: ExecFactory.newExecFromJavaClassName (each constructor fallback path) and newExecFromJavaCode, JavaRuntimeCompilation.compileCode (success + diagnostic-error paths), OperatorExecutor trait defaults (open/close/processTupleMultiPort/produceStateOnStart/processState/onFinish/onFinishMultiPort), and SourceOperatorExecutor trait defaults (processTuple/processTupleMultiPort empty + onFinishMultiPort delegating to produceTuple).

Priority

P3 - Low

Task Type

• Testing / QA