docs: def _http_req_body_serialize(self, body, content_type):
          """Conditionally serialize the request body value if mime_type is set
          and it's serializable.
  
          :param mixed body: The request body
          :param str content_type: The content type for the request body
          :raises: ValueError
  
          """
          if not body or not isinstance(body, (dict, list)):
              return body
          content_type = headers.parse_content_type(content_type)
          if content_type == CONTENT_TYPE_JSON:
              return self.__hcm_json.dumps(body)
          elif content_type == CONTENT_TYPE_MSGPACK:
              return self.__hcm_msgpack.packb(body)
          raise ValueError('Unsupported Content Type')