@:enum@:implinlineread onlyCHARACTERS:HBBufferClusterLevel
@:enum@:implinlineread onlyDEFAULT:HBBufferClusterLevel
@:enum@:implinlineread onlyMONOTONE_CHARACTERS:HBBufferClusterLevel
@:enum@:implinlineread onlyMONOTONE_GRAPHEMES:HBBufferClusterLevel