public static StringSet convertUrisToStrings(List<URI> targetUris){
  StringSet targetVolumeUris=new StringSet();
  for (  URI uri : targetUris) {
    targetVolumeUris.add(uri.toString());
  }
  return targetVolumeUris;
}

public static StringSet convertUrisToStrings ( List < URI > targetUris ) { StringSet targetVolumeUris = new StringSet ( ) ; for ( URI uri : targetUris ) { targetVolumeUris . add ( uri . toString ( ) ) ; } return targetVolumeUris ; }
converts a list of uris to a stringset of uri strings .
