presto-main/src/main/java/io/prestosql/operator/aggregation/RealHistogramAggregation.java/RealHistogramAggregation/merge
class RealHistogramAggregation:    @CombineFunction
    public static void merge(@AggregationState DoubleHistogramAggregation.State state, @AggregationState DoubleHistogramAggregation.State other)
    {
        DoubleHistogramAggregation.merge(state, other);
    }