presto-ml/src/main/java/io/prestosql/plugin/ml/StringClassifierAdapter.java/StringClassifierAdapter/StringClassifierAdapter
class StringClassifierAdapter:    public StringClassifierAdapter(Classifier<Integer> classifier, Map<Integer, String> labelEnumeration)
    {
        this.classifier = requireNonNull(classifier, "classifier is is null");
        this.labelEnumeration = requireNonNull(labelEnumeration, "labelEnumeration is null");
    }