message: Work around a crash with R8
diff: @@ -77,6 +77,11 @@ class LevelChecker {
  anno->type() == s_requires_api_new ||
  anno->type() == s_target_api)) {
  const auto& elems = anno->anno_elems();
  + // xxx: @androidx.annotation.RequiresApi() can not be compiled by javac,
  + // it should have argument. But we get such annotation after running R8.
  + if (elems.empty()) {
  + return -1;
  + }
  always_assert(elems.size() == 1);
  const DexAnnotationElement& api_elem = elems[0];
  always_assert(api_elem.string == DexString::get_string("api") ||
  