@Test
  void nullsAndOptionals() {
    repository.insert(generator.get().withId("id1").withValue("val1").withOptional("opt1").withNullable("null1"));

    repository.update(stringHolder.id.is("id1"))
            .set(stringHolder.optional, Optional.empty())
            .set(stringHolder.nullable, null)
            .execute();

    TypeHolder.StringHolder hol1 = repository.find(stringHolder.id.is("id1")).one();
    check(hol1.value()).is("val1");
    check(hol1.optional()).is(Optional.empty());
    check(hol1.nullable()).isNull();
  }
Tests for update operation(s) which include a filter (query).
See {@link org.immutables.criteria.backend.StandardOperations.UpdateByQuery}
criteria/common/test/org/immutables/criteria/typemodel/UpdateByQueryTemplate.java