The maven wrapper we ship is using 3.6.3, which is rather old. We should update the wrapper to a newer version (3.9.x, where x might bear some discussion) and, perhaps, update the documentation to reflect the version requirement change. Along with this, we should remove the .mvn/wrapper/maven-wrapper.jar and change the .mvn/wrapper/maven-wrapper.properties should look something like this:

wrapperVersion=3.3.4
distributionType=only-script
distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.12/apache-maven-3.9.12-bin.zip

The scripts will need to be updated as well.

Most of this can be done by simply running mvn -N wrapper:wrapper.