message: still return the nullptr if nullptr was passed
diff: @@ -389,10 +389,10 @@ template<>
  struct ApiClient::TypeInterpretation<oatpp::Boolean> {
  static oatpp::String toString(const oatpp::String &typeName, const oatpp::Boolean &parameter) {
  (void) typeName;
  - if(parameter.get() != nullptr) {
  + if(parameter != nullptr) {
  return utils::conversion::boolToStr(*parameter);
  }
  - return oatpp::String("false", 5, false);
  + return nullptr;
  }
  };
  