RFR: Update parser tests

[Vicente Romero]

On Fri, 19 Dec 2025 16:58:39 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

> This PR updates the parser tests to reflect the latest changes in the programming model.
> This led to minor parser tweaks to javac parser, to make sure that sensible error messgaes were being reported when null-restricted types are used in the wrong place.

lgtm

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Marked as reviewed by vromero (Committer).

PR Review: https://git.openjdk.org/valhalla/pull/1847#pullrequestreview-3599430496