@Override
  public boolean unregisterListener(ProcedureStoreListener listener) {
    return listeners.remove(listener);
  }
Change the state to 'isRunning', returns true if the store state was changed, false if the
store was already in that state.
@param isRunning the state to set.
@return true if the store state was changed, otherwise false.
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/store/ProcedureStoreBase.java