presto-main/src/main/java/io/prestosql/operator/aggregation/MergeHyperLogLogAggregation.java/MergeHyperLogLogAggregation/combine
class MergeHyperLogLogAggregation:    @CombineFunction
    public static void combine(@AggregationState HyperLogLogState state, @AggregationState HyperLogLogState otherState)
    {
        merge(state, otherState.getHyperLogLog());
    }