Function containsKey

src/ArduinoJson/Object/JsonObject.hpp:168–171

            detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
  ARDUINOJSON_DEPRECATED("use obj[key].is<T>() instead")
  bool containsKey(const TString& key) const {
    return detail::ObjectData::getMember(data_, detail::adaptString(key),
                                         resources_) != 0;
  }

  // DEPRECATED: use obj["key"].is<T>() instead
  // https://arduinojson.org/v7/api/jsonobject/containskey/