[Java] Avoid covariant ByteBuffer method references - #9225
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Java 9 added covariant ByteBuffer overrides for mutating methods such as clear(), position(int), limit(int), flip(), and rewind(). When these sources are compiled on a newer JDK without --release 8, javac emits references to those newer signatures, which are absent from Android API stubs and cause R8/ProGuard missing-method failures. Invoke the inherited methods through Buffer so the generated bytecode uses signatures supported by Java 8 and Android. This is behavior-preserving and allows downstream Java and Kotlin targets to use newer bytecode levels.
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Summary
Wehn using a different build system to compile Java from source, it's easy to get tripped up if your toolchain's default target release is > 8. Specifically ProGuard trips up due to covariant overrides for methods, specifically
clear(),position(int),limit(int),flip(), andrewind().We can route
ByteBuffercalls through theirBufferbase type to preserve behavior, while emittingjava.nio.Buffersignatures.Testing