code: public WebSocket sendClose(int closeCode, String reason)
      {
          return sendFrame(WebSocketFrame.createCloseFrame(closeCode, reason));
      }
docs: Send a close frame to the server.
  
  <p>
  This method is an alias of {@link #sendFrame(WebSocketFrame)
  sendFrame}{@code (WebSocketFrame.}{@link
  WebSocketFrame#createCloseFrame(int, String)
  createCloseFrame}{@code (closeCode, reason))}.
  </p>
  
  @param closeCode
  The close code.
  
  @param reason
  The close reason.
  Note that a control frame's payload length must be 125 bytes or less
  (RFC 6455, <a href="https://tools.ietf.org/html/rfc6455#section-5.5"
  >5.5. Control Frames</a>).
  
  @return
  {@code this} object.
  
  @see WebSocketCloseCode