Hi @aravindhrs,
you only have to pass the variable when you start the overall process instance.
No listener needed.
This should start successfully:
ProcessInstance processInstance = processEngine().getRuntimeService().startProcessInstanceByKey(PROCESS_DEFINITION_KEY,
withVariables("taskResolveDate", subprocessStartDate,
"candidateUsers", "demo",
"candidateGroups", "management"));
Cheers, Ingo