code: @Override
      public void chainQuiesced(ChainData chainData) {
          int oldState = chainState.getAndSet(ChainState.QUIESCED.val);
          if (oldState > ChainState.QUIESCED.val) {
              quiesceChain();
          }
      }
docs: ChainEventListener method.
  This method can not be synchronized (deadlock with update/stop).
  Rely on CFW synchronization of chain operations.