presto-main/src/main/java/io/prestosql/sql/planner/EffectivePredicateExtractor.java/Visitor/visitSemiJoin
class Visitor:        @Override
        public Expression visitSemiJoin(SemiJoinNode node, Void context)
        {
            // Filtering source does not change the effective predicate over the output symbols
            return node.getSource().accept(this, context);
        }