presto-main/src/main/java/io/prestosql/operator/aggregation/state/DigestAndPercentileArrayStateFactory.java/DigestAndPercentileArrayStateFactory/getGroupedStateClass
class DigestAndPercentileArrayStateFactory:    @Override
    public Class<? extends DigestAndPercentileArrayState> getGroupedStateClass()
    {
        return GroupedDigestAndPercentileArrayState.class;
    }