void createAndSetReturnFuture() {
    this.returnFuture = SettableFuture.create();
    if (getWmContext() != null) {
      getWmContext().setReturnEventFuture(returnFuture);
    }
  }
The actual state of the guaranteed task, and the update state, for the session.
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/WmTezSession.java