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