code: public synchronized void stop() throws IOException {
  		this.stopped = true;
  		if (this.server != null && this.waitingClient) {
  			this.server.close();
  			this.server = null;
  		}
  	}
docs: Stop the server instance by setting the stopped flag to true , the close the
  server instance if open.
  
  @throws IOException Signals that an I/O exception has occurred.