Mark quarkus:go-offline Maven mojo as thread-safe

[knutwannheden]

Description

We are using the quarkus:go-offline goal to pre-populate the local Maven repo in our CI builds. We have then configured GitLab to cache this Maven repo. Now, we would like to execute this Maven build in parallel (something like mvn dependency:go-offline io.quarkus:quarkus-maven-plugin::go-offline -T8 -Dmaven.artifact.threads=4). This works, but we see warnings like this printed to the console:

[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 Gluon - Integration Tests - User Context:
[WARNING]   io.quarkus:quarkus-maven-plugin:2.12.0.Final

Assuming that the go-offline goal is thread-safe already, it would only be a matter of changing @Mojo(name = "go-offline") to `@Mojo(name = "go-offline", threadSafe = true).

Implementation ideas

If the mojo is thread-safe, I could provide a PR.

[quarkus-bot]

/cc @quarkusio/devtools

[knutwannheden]

/cc @aloubyansky