public static SortedSet<String> extractOutcomeLabelsFromFeatureVectorFiles(File... files) throws IOException {
  SortedSet<String> result=new TreeSet<>();
  for (  File file : files) {
    result.addAll(extractOutcomeLabels(file));
  }
  return result;
}

public static SortedSet < String > extractOutcomeLabelsFromFeatureVectorFiles ( File ... files ) throws IOException { SortedSet < String > result = new TreeSet < > ( ) ; for ( File file : files ) { result . addAll ( extractOutcomeLabels ( file ) ) ; } return result ; }
extract all outcomes from featurevectorsfiles ( training , test ) that are in libsvm format - each line is a feature vector and the first token is the outcome label
