[lworld] RFR: 8372954: [lworld] Remove old implementation of the substitutability test method [v3]

[Frederic Parain]

On Tue, 3 Feb 2026 15:13:58 GMT, Chen Liang <liach at openjdk.org> wrote:

>> Could you update the comment above, replacing the mention to the pre-allocated default value with the a mention to the null-reset value? 
>> This is not related to the removal of the old substitutability method, but it's an easy cleanup to do.
>> Thanks.
>
> I have added the comments and briefly describes the field map records superclass fields so it is computed recursively and is present on AVCs.

There's still the comment about the pre-allocated default value, concept that doesn't exist anymore.
Instead, the slot is needed for the `.null_reset` static injected field, storing the value used to reset a nullable flat field when null is written to it.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/2012#discussion_r2759615093