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