public static Set<String> uriListToSet(List<URI> uris){
  Set<String> set=new HashSet<String>();
  if (uris != null && !uris.isEmpty()) {
    for (    URI uri : uris) {
      set.add(uri.toString());
    }
  }
  return set;
}

public static Set < String > uriListToSet ( List < URI > uris ) { Set < String > set = new HashSet < String > ( ) ; if ( uris != null && ! uris . isEmpty ( ) ) { for ( URI uri : uris ) { set . add ( uri . toString ( ) ) ; } } return set ; }
returns a set of strings from a list of uris
