docs: private void sendCloseMessage() {
  
          this.lock(() -> {
  
              TcpChannelHub.this.writeMetaDataForKnownTID(0, outWire, null, 0);
  
              TcpChannelHub.this.outWire.writeDocument(false, w ->
                      w.writeEventName(EventId.onClientClosing).text(""));
  
          }, TryLock.LOCK);
  
          // wait up to 1 seconds to receive an close request acknowledgment from the server
          try {
              final boolean await = receivedClosedAcknowledgement.await(1, TimeUnit.SECONDS);
              if (!await)
                  if (Jvm.isDebugEnabled(getClass()))
                      Jvm.debug().on(getClass(), "SERVER IGNORED CLOSE REQUEST: shutting down the client anyway as the " +
                              "server did not respond to the close() request.");
          } catch (InterruptedException ignore) {
              Thread.currentThread().interrupt();
          }
      }