Minor, but probably needs a JIRA.
After updating to Scala 2.12 I encountered this issue pretty quickly in tests: https://github.com/paul-hammant/paranamer/issues/17
Spark depends on jackson-module-paranamer 2.6.7 to match the other jackson deps, and that depends on paranamer 2.6. The bug above is fixed in 2.8.
However I noticed that, really, Spark uses jackson-module-scala 18.104.22.168, and that in turn actually depends on jackson-module-paranamer 2.7.9 (kind of odd), which already depends on 2.8.
So it seemed prudent to just not manually manage this dependency down. Then we still need to manage paranamer to 2.8 because Avro 1.7 pulls in 2.3.
But it all seems to work in a quick test. And it's necessary to get 2.12 working.