presto-parser/src/main/java/io/prestosql/sql/tree/SampledRelation.java/SampledRelation/SampledRelation
class SampledRelation:    public SampledRelation(NodeLocation location, Relation relation, Type type, Expression samplePercentage)
    {
        this(Optional.of(location), relation, type, samplePercentage);
    }