question: public synchronized AddressbookEntry remove ( String name , Set < String > categoriesToRemove ) { name = StringUtil . toLowerCase ( name ) ; AddressbookEntry currentEntry = entries . get ( name ) ; if ( currentEntry != null ) { Set < String > currentCategories = currentEntry . getCategories ( ) ; for ( String category : categoriesToRemove ) { currentCategories . remove ( category ) ; } AddressbookEntry changedEntry = new AddressbookEntry ( name , currentCategories ) ; entries . put ( name , changedEntry ) ; if ( ! currentEntry . equalsFully ( changedEntry ) ) { saveOnChange ( ) ; } return changedEntry ; } return null ; }
target:  Removes the given categories from the entry with the given name.