@Test
  void nullableIsNot() {
    repository.insert(generator.get().withId("id1").withValue(false).withNullable(false).withOptional(false));
    repository.insert(generator.get().withId("id2").withValue(true).withNullable(true).withOptional(true));
    repository.insert(generator.get().withId("id3").withValue(true).withNullable(null).withOptional(Optional.empty()));

    ids(holder.nullable.isNot(Optional.empty())).hasContentInAnyOrder("id1", "id2");
    ids(holder.nullable.isNot(Optional.of(false))).not().has("id1");
    ids(holder.nullable.isNot(Optional.of(true))).not().has("id2");
  }
Check for empty results on empty backend
criteria/common/test/org/immutables/criteria/typemodel/BooleanTemplate.java