Update to latest Error Prone, and limit its use to Java 21+.

[eamonnmcmanus]

No description provided.

[Marcono1234]

It seems you need this as well:

Suggested change

	<annotationProcessorPaths combine.self="override" />
	</configuration>

Plugins specified with -Xplugin:... are loaded from the annotation processors path (see documentation). The current configuration here only removes Error Prone from <compilerArgs> but not from <annotationProcessorPaths>. So the JDK still tries to load it.

Now as for why this was not an issue for JDK 11: There was a check which returned fast if no plugins were specified. In newer JDK versions this check was intentionally removed, see the JDK-8234211 and corresponding commit.

At least that is my understanding of it.

[eamonnmcmanus]

Thanks! Indeed, I couldn't figure out how this had worked before.

There's a later failure in building the proto tests but I'm hoping that one will be more tractable.

[eamonnmcmanus]

There's a later failure in building the proto tests but I'm hoping that one will be more tractable.

(That went away when I did mvn clean.)

[cpovirk]

Thanks, I get confused every time I see merging of configuration across pom.xml files, and I don't want to think about how long it would have taken me to figure out that that was even the right area to look.