ClassMetadataFactoryInterface::getMetadataFor()

If the method was called with the same class name (or an object of that class) before, the same metadata instance is returned.

If the factory was configured with a cache, this method will first look for an existing metadata instance in the cache. If an existing instance is found, it will be returned without further ado.

Otherwise, a new metadata instance is created. If the factory was configured with a loader, the metadata is passed to the {@link \Symfony\Component\Serializer\Mapping\Loader\LoaderInterface::loadClassMetadata()} method for further configuration. At last, the new object is returned.