docs: function _gpfInterfaceQueryThroughIUnknown(interfaceSpecifier, queriedObject) {
          var result = queriedObject.queryInterface(interfaceSpecifier);
          _gpfAssert(result === null || _gpfInterfaceIsImplementedBy(interfaceSpecifier, result), "Invalid result of queryInterface (must be null or an object implementing the interface)");
          return result;
      }