code: @Override
    protected HttpOperation generateHttpOperation (GenericRecord inputRecord, State state) {
      Map<String, String> keyAndValue = new HashMap<>();
      Optional<Iterable<String>> keys = getKeys(state);
      HttpOperation operation;
  
      if (keys.isPresent()) {
        for (String key : keys.get()) {
          String value = inputRecord.get(key).toString();
          log.debug("Http join converter: key is {}, value is {}", key, value);
          keyAndValue.put(key, value);
        }
        operation = new HttpOperation();
        operation.setKeys(keyAndValue);
      } else {
        operation = HttpUtils.toHttpOperation(inputRecord);
      }
      return operation;
    }
docs: Extract user defined keys by looking at "gobblin.converter.http.keys"
  If keys are defined, extract key-value pair from inputRecord and set it to HttpOperation
  If keys are not defined, generate HttpOperation by HttpUtils.toHttpOperation