code: protected void postCloseEvent(final WebSocketCloseCode closeCode, final String reason) {
          for (final WebSocketListener listener : listeners) {
              if (listener.onClose(this, closeCode, reason)) {
                  break;
              }
          }
      }
docs: Listeners will be notified about socket closing.
  
  @param closeCode closing code.
  @param reason optional closing reason.