presto-spi/src/main/java/io/prestosql/spi/predicate/TupleDomain.java/TupleDomain/simplify
class TupleDomain:    public TupleDomain<T> simplify()
    {
        if (isNone()) {
            return this;
        }

        Map<T, Domain> simplified = domains.get().entrySet().stream()
                .collect(toLinkedMap(Map.Entry::getKey, e -> e.getValue().simplify()));

        return TupleDomain.withColumnDomains(simplified);
    }