question: public static < T > void updateMappingToImmutableSet ( Map < T , Set < AnnotationMirror > > map , T key , Set < AnnotationMirror > newQual ) { Set < AnnotationMirror > result = AnnotationUtils . createAnnotationSet ( ) ; if ( ! map . containsKey ( key ) ) { result . addAll ( newQual ) ; } else { result . addAll ( map . get ( key ) ) ; result . addAll ( newQual ) ; } map . put ( key , Collections . unmodifiableSet ( result ) ) ; }
target:  See checkers.types.QualifierHierarchy#updateMappingToMutableSet(QualifierHierarchy, Map, Object, AnnotationMirror) (Not linked because it is in an independent project.