question: @ NotNull public static IElementType [ ] enumerate ( @ NotNull Predicate p ) { List < IElementType > matches = new ArrayList < IElementType > ( ) ; for ( IElementType value : ourRegistry ) { if ( value != null && p . matches ( value ) ) { matches . add ( value ) ; } } return matches . toArray ( new IElementType [ matches . size ( ) ] ) ; }
target:  Enumerates all registered token types which match the specified predicate.