investigate why JsonValue annotation does not work in Scala 3

[pjfanning]

These tests only pass when Scala 2 is used:

• https://github.com/FasterXML/jackson-module-scala/blob/master/src/test/scala-2.%2B/com/fasterxml/jackson/module/scala/ser/AnyValScala2SerializerTest.scala
• https://github.com/FasterXML/jackson-module-scala/blob/master/src/test/scala-2.%2B/com/fasterxml/jackson/module/scala/ser/JsonValueScala2Test.scala

[caarmen]

I was trying to debug the issue with @JsonValue being ignored with scala 3.

The way this works is mostly a mystery to me, but I did notice one difference, using the debugger, when running TestJsonValue with scala 2 vs 3.

I executed this in the debugger "Evaluate expression" tool

classOf[ValueClass].getMethod("value").getDeclaredAnnotations

With scala 2, it returns an array with one item. With scala 3, it returns an empty array.

Not sure how useful this is :)

[pjfanning]

Thanks @caarmen - that sounds like the likely cause. The Scala3 compiler has a few optimisations that has caused a few issues for jackson.

[caarmen]

Could this issue be related? https://github.com/lampepfl/dotty/issues/12492

[pjfanning]

I've also linked to https://github.com/FasterXML/jackson-databind/issues/3063

[pjfanning]

Looks like Scala 3.3 fixes this. Tested with https://github.com/FasterXML/jackson-module-scala/tree/scala-3.3

It is likely that jackson-module-scala will not be compiled with Scala 3.3 until maybe the 2.16.0 release but it is likely that using Scala 3.3 runtime should be enough to fix this for users.

[pjfanning]

Scala 3.3.0 is released. You should be able to use this any recent jackson-module-scala release with Scala 3.3.0. Upgrading to Scala 3.3.0 should be enough. See #635 for the formal uptake of Scala 3.3.0.