This requires Kotlin 1.2 versions of core and serialization (core-1.2 and serialization-1.2 respectively), which are just "shell" modules and which compile the existing source code with Kotlin 1.2. The 1.2 plugin does not work with the current version of Gradle and so the 1.2 compiler has to be called directly.
Now with two versions of Kotlin in the code base, each module needs to have its version manually specified to ensure a clean separation. Otherwise, the default Kotlin version can override 1.2 when needed.
Some of the code was tidied-up or improved to enable it to be cross-compiled. For post-1.2 APIs being used, they have been copied into core-1.2 with the same method signatures. OpenTelemetryComponent was moved to node-api, along with the dependency, to avoid also having a 1.2 version for the opentelemetry module.
