code: protected static String responseToJson(Response response) throws JsonProcessingException {
          ObjectMapper mapper = ApiModelMixinModule.setupObjectMapper(new ObjectMapper());
          mapper.enable(SerializationFeature.INDENT_OUTPUT);
          mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
          return mapper.writeValueAsString(response);
      }
docs: Converts a response to JSON string
  
  @param response {@link com.basistech.rosette.apimodel.Response Response} from RosetteAPI
  @return the json string.
  @throws JsonProcessingException if the Jackson library throws an error serializing.