presto-main/src/main/java/io/prestosql/operator/aggregation/AbstractMinMaxNAggregationFunction.java/AbstractMinMaxNAggregationFunction/specialize
class AbstractMinMaxNAggregationFunction:    @Override
    public InternalAggregationFunction specialize(BoundVariables boundVariables, int arity, Metadata metadata)
    {
        Type type = boundVariables.getTypeVariable("E");
        return generateAggregation(type);
    }