code: public RequestFuture<?> send(String content)
      {
          Checks.notBlank(content, "Content");
          Checks.check(content.length() <= 2000, "Content may not exceed 2000 characters!");
          return execute(newBody(new JSONObject().put("content", content).toString()));
      }
docs: Sends the provided text message to this webhook.
  
  @param  content
  The text message to send
  
  @throws java.lang.IllegalArgumentException
  If any of the provided message is {@code null}, blank or exceeds 2000 characters in length
  @throws java.util.concurrent.RejectedExecutionException
  If this client was closed
  
  @return {@link net.dv8tion.jda.core.requests.RequestFuture RequestFuture} representing the execution task,
  this will be completed once the message was sent.