gRPC generated java references javax.annotation.Generated which is not in Jakarta

[hutchig]

gRPC protobuf tools generate Java that has annotations that are NOT retained at runtime of
javax.annotation.Generated

Such java will not compile with Liberty in Jakarta 9/10 as that package is not present.
There are 2 possible solutions currently:
1 - Use the Eclipse transformer (The Liberty gRPC 1.0 guide stopped short of including this for simplicity's sake.)

2 - Add in a dependency, for example the gRPC read.me recommends:

grpc/grpc-java#9179 (comment)

<dependency> <!-- necessary for Java 9+ -->
  <groupId>org.apache.tomcat</groupId>
  <artifactId>annotations-api</artifactId>
  <version>6.0.53</version>
  <scope>provided</scope>
</dependency>

(The Liberty gRPC guide ++ looks like it wants to use that route:
OpenLiberty/guide-grpc-intro#43 )

3. As it's an annotation that is not retained at RUNTIME could we not bundle it up and pull it in
   to the compile dependencies IFF gRPC and Jakarta EE9/10... etc is the mode?
   After all tomcat are bundling it without 'owning' the javax.annotation package so we should
   be able do the same in a way that avoids it being on the compile classpath if NOT Jakarta?

[hutchig]

The actions/questions here are:
1:
Do we want to ship a guide that has to make use of Tomcat to compile?

2:
If we can find a way for the grpc generated code to 'just work' can we
(can I have the green light to) create a small PR that bundles the javax Generated
annotation as part of gRPC for Jakarata compile path?

I would think we would want to be careful NOT to ship javax.annotations.Generated if
the user was getting it from the pre-Jakarta source but as it is not retained at runtime
I am not sure exactly how careful we would really need to be.

[hutchig]

https://search.maven.org/artifact/javax.annotation/javax.annotation-api/1.3.2/jar
might be an alternative source of the annotation.

[hutchig]

The grpc guide has been changed to pull in the javax package without doing so via tomcat, so this is no longer an urgent design issue. I will see if I can include the same include they use ONLY if we are in Jakarta mode as part of the base feature.

[cbridgha]

I put this in parked for now - please let me know if status changes...

[hutchig]

There are two follow on actions for this:
1 - see if I can include the https://search.maven.org/artifact/javax.annotation/javax.annotation-api/1.3.2/jar if we are in the Jakarta mode and @Generated would not be present otherwise
2 - Write a PR on the grpc readme to replace references to Tomcat with javac.annotation-api.