message: Warn when we can't find keep annotations
  Summary: We recently ran into an issue where Proguard deleted DoNotStrip for instagram. Let's warn the user when we can't find the keep annotation that the config asked for
diff: @@ -417,7 +417,11 @@ void init_permanently_reachable_classes(
  for (auto const& annostr : annotations) {
  DexType* anno = DexType::get_type(annostr.c_str());
  - if (anno) annotation_types.insert(anno);
  + if (anno) {
  + annotation_types.insert(anno);
  + } else {
  + fprintf(stderr, "WARNING: keep annotation %s not found\n", annostr.c_str());
  + }
  }
  keep_annotated_classes(scope, annotation_types);
  