docs: public void shutdown(){
          synchronized(this){
              if(! isShutdown){
                  if (directoryManagerFactory != null) {
                      if (directoryManagerFactory instanceof Closable) {
                          ((Closable) directoryManagerFactory).stop();
                      }
                      directoryManagerFactory = null;
                  }
                  if (client != null) {
                      client.close();
                      client = null;
                  }
                  this.isShutdown = true;
              }
          }
      }