Integrated: Fix signature attribute generation for null restrictions

[Maurizio Cimadamore]

On Fri, 19 Dec 2025 18:21:32 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> The code in `Types` is already correctly handling null restrictions.
> There's only a minor problem with the flag to enable null restriction not being passed recursively in nested call (e.g. for method signatures).
> 
> Since I was there, I also dropped signature generation code for type variable declarations.

This pull request has now been integrated.

Changeset: e578dced
Author:    Maurizio Cimadamore <mcimadamore at openjdk.org>
URL:       https://git.openjdk.org/valhalla/commit/e578dced80e295dbe756970db5b685a038384be1
Stats:     24 lines in 1 file changed: 0 ins; 20 del; 4 mod

Fix signature attribute generation for null restrictions

Reviewed-by: vromero

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PR: https://git.openjdk.org/valhalla/pull/1848