Allow to suppress null values in serialization

In order to minimize my response body size from my REST controllers, I would like to be able to supress all null values when serializing to JSON, however when I changed my ObjectMapper to use Include.NON_NULL by default I found that suppressNull is hard coded to false in JsonNullableSerializer. This results in considerable bloat.

You might wonder why I don't use JsonNullable.undefined() instead. I have an OpenAPI schema with 679 different fields, of which 174 are nullable. Keeping track of which fields are nullable, and changing all of those converter classes to use JsonNullable is quite a lot of work. On top of that, the Java models generated with openapi-generator-maven-plugin do not create fluent setters for JsonNullable.

It would save me a lot of effort if JsonNullableSerializer would just respect suppressNull, is that something you would agree to change?
If not, I could submit a PR to add a setting to JsonNullableModule to toggle whether suppressNull should be respected?

Start by reading JsonNullableSerializer and JsonNullableModule to understand how suppressNull is currently handled, then inspect the repository's existing serialization tests. Define whether the change should make the serializer respect ObjectMapper's Include.NON_NULL setting or add a module-level toggle, and consider the work done when the chosen behavior is covered by tests.