code: public WebhookMessageBuilder setUsername(String username)
      {
          this.username = Helpers.isBlank(username) ? null : username;
          return this;
      }
docs: Sets the username that should be used for the resulting message.
  <br>This will override the default username of the webhook.
  
  @param  username
  The username to use for this message
  
  @return The current WebhookMessageBuilder for chaining convenience