`javadoc:aggregate-jar` is not marked as thread-safe

[JackPGreen]

Affected version

3.12.0

Bug description

The documentation says the javadoc:aggregate-jar goal isn't thread safe, leading to warnings when executed with a parallel build:

Warning: *****************************************************************
Warning: * Your build is requesting parallel execution, but this *
Warning: * project contains the following plugin(s) that have goals not *
Warning: * marked as thread-safe to support parallel execution. *
Warning: * While this /may/ work fine, please look for plugin updates *
Warning: * and/or request plugins be made thread-safe. *
Warning: * If reporting an issue, report it against the plugin in *
Warning: * question, not against Apache Maven. *
Warning: *****************************************************************
Warning: The following plugins are not marked as thread-safe in my-project:
Warning: org.apache.maven.plugins:maven-javadoc-plugin:3.12.0
Warning:
Warning: Enable debug to see precisely which goals are not marked as thread-safe.
Warning: *****************************************************************

Other goals are declared thread-safe:

maven-javadoc-plugin/src/main/java/org/apache/maven/plugins/javadoc/JavadocNoForkReport.java

Line 45 in a308a14

@Mojo(name = "javadoc-no-fork", requiresDependencyResolution = ResolutionScope.COMPILE, threadSafe = true)

So I suspect that rather than being not thread-safe, this annotation is simply missing from the other goals?