False negative on implementation dependency

I don't have a repro project but locally we are getting a false negative.

`projectHealth` will tell me
```
You asked about the dependency 'org.jetbrains.kotlinx:kotlinx-coroutines-rx2:1.6.4'.
You have been advised to change this dependency to 'testImplementation' from 'implementation'.
```
but when the dependency is set to `testImplementation`, I get compilation errors.

How could I debug that to ideally get it fixed upstream?

Start by creating a minimal reproduction for the kotlinx-coroutines-rx2:1.6.4 dependency and compare projectHealth's advice with the compilation errors after changing implementation to testImplementation. Done means the dependency scope is correctly identified and the resulting project compiles without the false-negative advice.

Written by the indexing model from the issue text.