@Nullable
  protected TState getCurrentState() {
    if (!states.isEmpty()) {
      if (states.getLast() == EOF_STATE) {
        return null;
      }
      return getState(states.getLast());
    }
    return getInitialState();
  }
Used by the default implementation of abort() to know if the current state can be aborted and
rollback can be triggered.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/procedure/impl/StateMachineProcedure.java