public Set<String> find(T object){
  if (!locations.containsKey(object)) {
    locations.put(object,new HashSet<>());
  }
  return Collections.unmodifiableSet(locations.get(object));
}

public Set < String > find ( T object ) { if ( ! locations . containsKey ( object ) ) { locations . put ( object , new HashSet < > ( ) ) ; } return Collections . unmodifiableSet ( locations . get ( object ) ) ; }
find the names of a given object .
