code: protected String serializeBody(Request request)
      {
          try
          {
              return objectMapper.writeValueAsString(request.getRequestBody());
          }
          catch (JsonProcessingException e)
          {
              throw new ClientMarshallingException("Error writing request.",e);
          }
      }
docs: Serialize the request body
  @param request The data service request
  @return The JSON representation of the request