Oh okay. So it sounds like many languages, including Java, originally
generated code where every message's type was placed into a single
generated file (a file per .proto file). For Java, you can only have one
public class per file, so the outer class technique was used so that it
could be the
I googled this and found questions like "How to use Protobuf message as
java class without a java outer class?" (
https://stackoverflow.com/questions/60312156/how-to-use-protobuf-message-as-java-class-without-a-java-outer-class)
which talk about how one might tweak their Protobuf Java code