presto-main/src/main/java/io/prestosql/operator/aggregation/state/DigestAndPercentileArrayStateFactory.java/DigestAndPercentileArrayStateFactory/createGroupedState
class DigestAndPercentileArrayStateFactory:    @Override
    public DigestAndPercentileArrayState createGroupedState()
    {
        return new GroupedDigestAndPercentileArrayState();
    }