presto-main/src/main/java/io/prestosql/sql/planner/DomainTranslator.java/DomainTranslator/visitNullLiteral
class DomainTranslator:        @Override
        protected ExtractionResult visitNullLiteral(NullLiteral node, Boolean complement)
        {
            return new ExtractionResult(TupleDomain.none(), TRUE_LITERAL);
        }