code: public T fromJson(byte[] json)
              throws IllegalArgumentException
      {
          try {
              return mapper.readValue(json, javaType);
          }
          catch (IOException e) {
              throw new IllegalArgumentException(format("Invalid JSON bytes for %s", javaType), e);
          }
      }
docs: Coverts the specified json bytes (UTF-8) into an instance of type T.
  
  @param json the json bytes (UTF-8) to parse
  @return parsed response; never null
  @throws IllegalArgumentException if the json bytes can not be converted to the type T