Does this have to do with warning for test phase, when actually there are no tests at all?

mvn version 3.9.1

[INFO] --- surefire:2.22.2:test (default-test) @ ..... ---
[WARNING] Parameter 'localRepository' is deprecated core expression; Avoid use of ArtifactRepository type. If you need access to local repository, switch to '${repositorySystemSession}' expression and get LRM from it instead.
[INFO] No tests to run.

solved with latest 3.0.0 https://maven.apache.org/surefire/maven-surefire-plugin/

e.g. with Spring Boot

<maven-surefire-plugin.version>3.0.0</maven-surefire-plugin.version>

How should https://github.com/cloudbees/maven-license-plugin/blob/b58872cc1f4062ec01ca903d9a5546cc3b85a748/src/main/java/com/cloudbees/maven/license/ProcessMojo.java#L179 be adapted? The deprecation notice says to switch to repositorySystemSession.getLocalRepository(), but that does not compile:

java: incompatible types: org.eclipse.aether.repository.LocalRepository cannot be converted to org.apache.maven.artifact.repository.ArtifactRepository

1. drop localRepository, remove buildingRequest.setLocalRepository(localRepository);
2. instead grab RepositorySystemSession "${repositorySystemSession}"
3. on ProjectBuildingRequest setSession from 2 and remove dropped setter from 1
4. test it

on ProjectBuildingRequest setSession from 2

The setSession method does not exist, but a setRepositorySession exists. But why should I call that when session.getProjectBuildingRequest() already calls it a few lines above?

Yup, setRepositorySession... if you are sure it is there, then not needed.

Just for future: please use ML for asks like this one :)
https://maven.apache.org/mailing-lists.html

This migration was poorly documented. What you asked me to do had nothing to do with the instructions in the deprecation warning. I think it was appropriate to complain about that in this PR.

Resolve #9271