question: private void listDirectory ( File directory , RelativeDirectory subdirectory , Set < JavaFileObject . Kind > fileKinds , boolean recurse , ListBuffer < JavaFileObject > resultList ) { File d = subdirectory . getFile ( directory ) ; if ( ! caseMapCheck ( d , subdirectory ) ) return ; File [ ] files = d . listFiles ( ) ; if ( files == null ) return ; if ( sortFiles != null ) Arrays . sort ( files , sortFiles ) ; for ( File f : files ) { String fname = f . getName ( ) ; if ( f . isDirectory ( ) ) { if ( recurse && SourceVersion . isIdentifier ( fname ) ) { listDirectory ( directory , new RelativeDirectory ( subdirectory , fname ) , fileKinds , recurse , resultList ) ; } } else { if ( isValidFile ( fname , fileKinds ) ) { JavaFileObject fe = new RegularFileObject ( this , fname , new File ( d , fname ) ) ; resultList . append ( fe ) ; } } } }
target:  Insert all files in subdirectory subdirectory of directory directory which match fileKinds into resultList