Evaluate not only compilerArguments but also compilerArgs
compilerArguments was deprecated. Now you should rather use compilerArgs to configure eg. the properties file. The tricky thing is that the latter gets a List of Strings. There are multiple ways to configure that within a pom.xml. Also, it should not only consider global plugin configuration settings but also execution specific configurations. The code at https://github.com/lastnpe/eclipse-external-annotations-m2e-plugin/blob/master/eclipse-external-annotations-m2e-plugin.core/src/org/lastnpe/m2e/core/configurator/ClasspathConfigurator.java#L333 needs to be adjusted.
@kwin sorry I'm only seeing & reacting to this now! Would you be willing to raise a PR for this?
@kwin if you would be interested in raising a PR for this, that would certainly still be interesting!
If you use a recent Maven version like 3.9.1 it will also start logging warnings if you use deprecated plug-in options:
[WARNING] Parameter 'compilerArguments' is deprecated: use {@link #compilerArgs} instead.
@wborn if you would be interested in raising a PR for this, I'm happy to click Merge on it.