code: public void close() {
          done = true;
          connected = false;
          synchronized (this) {
              try {
                  if (socket != null) {
                      if (traceLevel >= ctrlThreshold) {
                          System.out.println("-> CLOSE");
                      }
                      socket.close();
                  }
              } catch (final IOException e) { /* ignore socket close errors */
              } finally {
                  socket = null;
              }
          }
      }
docs: Close the connection to the remote node.