There is a special section which describes special information needed for applying this rule within Android. Per your analysis, currently all in Java, however I would expect in the future we will have this for other languages, and for developers it would be useful to filter just for the language they are working in… So different tags for different languages will be useful (at least, eventually if not now). In at least one case, the section actually talks about why the rule is *not* Android-applicable, I think we need to use a different label in this case.
Android-implementation-detail
Same as 'Android-implementation-detail-java'
not-android-applicable-java
It is a Java rule or recommendation, but not Android-applicable (per chart of Android applicability).
android
It is applicable to Android. There are very few Java rules/recs that are NOT applicable to Android. However, not all of the Android-applicable Java rules/recs require special implementation details.
unknown
Android applicability has not yet been determined.
