presto-main/src/main/java/io/prestosql/operator/aggregation/histogram/GroupedHistogramState.java/GroupedHistogramState/GroupedHistogramState
class GroupedHistogramState:    public GroupedHistogramState(Type keyType, int expectedEntriesCount)
    {
        typedHistogram = new GroupedTypedHistogram(keyType, expectedEntriesCount);
    }