presto-main/src/main/java/io/prestosql/sql/planner/iterative/rule/TransformUncorrelatedSubqueryToJoin.java/TransformUncorrelatedSubqueryToJoin/filter
class TransformUncorrelatedSubqueryToJoin:    private Optional<Expression> filter(Expression criteria)
    {
        if (criteria.equals(TRUE_LITERAL)) {
            return Optional.empty();
        }

        return Optional.of(criteria);
    }