/**
  * Returns the request's body.
  *
  * Returns empty string if request is not a entity enclosing inteface.
  *
  * @param RequestInterface $request Request to get body from.
  *
  * @return string
  */
 protected function getRequestBody($request)
 {
     return $request instanceof EntityEnclosingRequestInterface ? (string) $request->getBody() : '';
 }