private static function setModelClassMappings() { if (static::$modelClassMapping === null) { static::$modelClassMapping = array(); foreach (static::getModelClasses() as $modelClassName) { $entity = $modelClassName::$entityType; $bundle = $modelClassName::$bundle; if (empty($entity)) { throw new InvalidTypeException('Entity Type not defined for ' . $modelClassName); } $key = Model::getKeyForEntityAndBundle($entity, $bundle); static::$modelClassMapping[$key] = $modelClassName; } } }