Java @Nullable annotations in generated classes
We use Checkerframework to ensure a project's null-safety.

In our case, this is done by assuming that all fields and parameters are annotated by `@NotNull` implicitly while nullable fields and parameters are explicitly annotated by a `@Nullable` annotations.

The generated Kaitai classes do have some nullable constructor parameters which fail the null-safty check in a project in which Checkerframework is enabled.

It would be nice to be able to instruct Kaitai to add a (customizable) `@Nullable` annotation where appropriate.
