API compatibility check in pipeline

[viartemev]

Use case
There are several issues related to API incompatible changes:

• Fix KotlinModule constructor ABI #343
• 2.9.7 introduces binary compatibility issue in KotlinModule constructor #178
• 2.10 introduces another binary compatibility issue in KotlinModule constructor #279

Describe the solution you'd like
A pipeline should check if new version of the library compatible with old versions.
There is a tool for it: https://github.com/siom79/japicmp
japicmp is customizable and could build if a new version is incompatible.

[cowtowncoder]

I would be interested in seeing how this works in practice: +1 for addressing what has become an issue with the module.

[GreyTeardrop]

There's also Kotlin's own https://github.com/Kotlin/binary-compatibility-validator but it's available only as a Gradle plugin at the moment.

[k163377]

It is closed as compatibility is believed to be ensured by the grid test added below.
#588

[cowtowncoder]

@k163377 Actually I think this is different from Matrix build -- question here is about Kotlin module API changing across module versions (regardless of kotlin-core).

And this is the actual issue for which japicmp maven plugin was added, and which guards against all kinds of changes, even minor ones, giving (IMHO) what amounts to false positives.
Related to CI failure you observed wrt ReflectionCache change (removal of individual cache fields).