minor #30965 Prepare for the new serialization mechanism (fancyweb)
minor #30965 Prepare for the new serialization mechanism (fancyweb)

This PR was merged into the 4.3-dev branch.

Discussion
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Prepare for the new serialization mechanism

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

#eufossa

Should I maybe split this component by component ?

https://wiki.php.net/rfc/custom_object_serialization has been accepted.

Best viewed in "split" mode.

This work is kind of required for https://github.com/symfony/symfony/issues/30304 so we don't trigger 30 deprecations from our own code base.

Commits
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d412e77a9c Prepare for the new serialization mechanism

symfony/Validator