BeanDeserializerModifier::updateBuilder doesn't work for immutable beans

[herkrath]

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Describe the bug

Custom JsonDeserializers set via BeanDeserializerModifier::updateBuilder work for mutable beans only. They are ignored for immutable ones. This issue originates from #4351.

Version Information

At least 2.14 - 2.16.1, likely since much longer

Reproduction

Explanatory unit tests, as well as a potential fix, are part of my PR #4357.

Expected behavior

Custom JsonDeserializers set via BeanDeserializerModifier::updateBuilder shall work for mutable and immutable beans.

Additional context

Note: My suggested fix does work for this very scenario and doesn't break any of the existing unit tests. However, it may not fix other, related issues with BeanDeserializerModifier. Also, as I don't know every single Jackson feature and this part of the code is very delicate and complex, it may interfere with other features. Please review detailed.

[cowtowncoder]

Added failing test from #4357 -- timing-wise cannot fix for 2.17 due to release going out soon but depending on things might be possible for 2.17.x patch (if not, 2.18)