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