Hi, 

Starting with 1.4.2 I spotted an issue when defining a custom `LogbackMDCAdapter`.

In short, this change https://github.com/qos-ch/logback/commit/7e3e2ae770c19724b0714c7f48fd33bbc6791c7e#diff-e5a738c3ab37fbeacbb433d7d7171c51c6058623c377c8549191ad47ca5020f3R177 changed the definition of the `setContextMap` to be unchecked (`Map` vs. `Map<String, String>`).

This is breaking custom adapters in Scala. I setup a minimal repro here: https://github.com/AL333Z/logback-issue/blob/main/src/main/scala/MyLogbackAdapter.scala#L5-L12

Restoring the definition to be `public void setContextMap(Map<String, String> contextMap)` should restore the functionality.