code: String getBody(Object object, ContentType contentType) {
          if (contentType == ContentType.APPLICATION_FORM_URLENCODED) {
              return jsonToUrlEncodedString((JsonObject) new JsonParser().parse(gson.toJson(object)));
          }
  
          return gson.toJson(object);
      }
docs: This method is used to get a serialized object into its equivalent JSON representation.
  
  @param   object
  {@code Object} the body object.
  
  @param   contentType
  {@ContentType} the content type header.
  
  @return  {@code String}