code: public static ConfigurableJsonFluentAssert assertThatJson(Object json) {
          return new ConfigurableJsonFluentAssert(convertToJson(json, ACTUAL), getPathPrefix(json));
      }
docs: Creates a new instance of <code>{@link JsonFluentAssert}</code>.
  It is not called assertThat to not clash with StringAssert.
  The json parameter is converted to JSON using ObjectMapper.
  
  @param json
  @return new JsonFluentAssert object.