Following the docs, I've added:
FirebaseCrashlytics.getInstance().setCustomKey("my_string_key", "foo" /* string value */)
I'm using the latest version of crashlytics:
implementation platform('com.google.firebase:firebase-bom:30.3.1')
implementation 'com.google.firebase:firebase-crashlytics'
implementation 'com.google.firebase:firebase-analytics'
I've forced a crash like this:
throw RuntimeException("Test Crash6")
The crash is showing up in the dashboard, but not the custom key:



