question: protected Set < AnnotationMirror > findBottoms ( Map < AnnotationMirror , Set < AnnotationMirror > > supertypes ) { Set < AnnotationMirror > possibleBottoms = AnnotationUtils . createAnnotationSet ( ) ; possibleBottoms . addAll ( supertypes . keySet ( ) ) ; for ( Set < AnnotationMirror > supers : supertypes . values ( ) ) { possibleBottoms . removeAll ( supers ) ; } return possibleBottoms ; }
target:  Infer the bottoms of the subtype hierarchy.  Simple finds the qualifiers that are not supertypes of other qualifiers.