InvalidDefinitionExceptions using kotlin 1.6.0

Describe the bug Hello! First, thanks for maintaining the project and all the work involved.

Since we updated Kotlin (kgp) in our project to 1.6.0 we started to see issues with r8 related with Jackson and Kotlin. Suddenly, the library is unable to de-serialize responses, mapped as data classes from our backend with the following errors

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of [...any dto class...] (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

To Reproduce Set minifyEnabled to true in your build script using kgp 1.6.0

Expected behavior A clear and concise description of what you expected to happen.

Versions Kotlin: 1.6.0 Jackson-module-kotlin: 2.13.0 Jackson-databind: 2.13.0

Additional context

Also using:

implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version" (1.6.0)

[C2H6O]

Thanks @k163377, you pointed me in the right direction!

Apparently this is an R8 bug: https://issuetracker.google.com/issues/206855609

Following https://issuetracker.google.com/issues/206855609#comment9 solved the issue.

[RabieJradi]

I’ve been having the same issue as well. I worked around the issue by marking all my classes with a no arg annotation using this compiler plugin https://kotlinlang.org/docs/no-arg-plugin.html#gradle. Definitely not an ideal solution, but I couldn’t get any added proguard exemption rules to have an effect. I’ve tried many different rules, including keeping entire packages both from fasterxml paths and my own code with no luck. I can confirm that the issue disappears if proguard is disabled, but that is not a feasible solution for me unfortunately.