code: protected LogoutHttpMessage getLogoutHttpMessageToSend(final SingleLogoutRequest request, final SingleLogoutMessage logoutMessage) {
          return new LogoutHttpMessage(request.getLogoutUrl(), logoutMessage.getPayload(), this.asynchronous);
      }
docs: Gets logout http message to send.
  
  @param request       the request
  @param logoutMessage the logout message
  @return the logout http message to send