externalInitiatedEventId
The ID of the SignalExternalWorkflowExecutionInitiated
event corresponding to the SignalExternalWorkflow
decision to signal this workflow execution.The source event with this ID can be found in the history of the source workflow execution. This information can be useful for diagnosing problems by tracing back the chain of events leading up to this event. This field is set only if the signal was initiated by another workflow execution.