Invalid reflective access in Enumeration serialization on Scala 3.8+

[WojciechMazur]

See scala/scala3#25119

In the Scala 3 Open Community Build we've seen that this project was failing at runtime. It is caused by reflectve access to $outer filed of Enumeration.Value class which is under Scala 2 was published as public, but in the Scala 3 it's emitted as private.
The change has started be active since Scala 3.8 which introduces Scala standard library (including Enumeration) compiled using Scala 3.8

The unsafe access to private $outer member should be fixed on the library end my modifing access to that field, rewriting logic or deprecating these usages

[pjfanning]

Thanks @WojciechMazur. Is it intended for Scala 3 to continue to support Scala 2 Enumerations? Many users have long avoided them anyway. I'd recommend that Jackson users use Scala3 enums, Java enums or Enumeratum (there is https://github.com/pjfanning/jackson-module-enumeratum)

[WojciechMazur]

Technically it was never deprecated and still is supported by Scala 3, partially because until 3.8 standard library was still in the Scala 2 territory. It might become officially deprecated since Scala 3.10 as this is the first version that would allow for modifications of stdlib.
Personally I'd recommend the same choices as well as the alternative. The issue cought our attention only due to the failing tests

[pjfanning]

Fixed in 3.x branch. I don't yet plan to backport to the 2.x branch. Let's see if 2.x users complain.