presto-ml/src/main/java/io/prestosql/plugin/ml/LearnStateFactory.java/GroupedLearnState/getLabels
class GroupedLearnState:        @Override
        public List<Double> getLabels()
        {
            List<Double> labels = labelsArray.get(groupId);
            if (labels == null) {
                labels = new ArrayList<>();
                size += ARRAY_LIST_SIZE;
                // Assume that one parameter will be set for each group of labels
                size += SVM_PARAMETERS_SIZE;
                labelsArray.set(groupId, labels);
            }
            return labels;
        }