With the maven-eclipse-plugin, using mvn eclipse:eclipse, you can specifiy eclipse project natures and builders that will automatically be added to the eclipse project.
Earlier versions of m2eclipse used the configuration block of the maven-eclipse-plugin and also let you activate natures and builders using the same mechanisms. This seems to no longer be the case because a) I can't find any reference to maven-eclipse-plugin in the m2eclipse sources and b) it just doesn't work :-)
So this is my question: is there any way to configure the eclipse project generated by m2eclipse from the pom.xml? Specifically: project builders and natures, but I'd be interested in other options as well.
I have now implemented this as a maven plugin I call maven-eclipseconf-plugin. Unfortunately it's proprietary work for a client, so I can't share it. But let me describe what I do:
Tied to the lifecycle verify, I check for the existence of an eclipse .project file. If it's there, I check it for the presence of the builders and natures I want to automatically add (and you can deactivate this behavior by using a maven property or a stop file with a configurable name). You can also define configuration files that will be written (like .pmd, which is related to this other question of mine). The contents of the Configuration files can be specified inline, it can come from an external file, or from a URL. I also tried to introduce variable substitution in the config files where a special placeholder would be replaced with a multi-moduke-project's root folder, but I had to give up on that approach.
Anyway, the plugin gives me pretty much all the functionality of the maven-eclipse-plugin I ever used (of course there is a lot more though) and I'm happy with that. Perhaps I will build something similar once more in open source when this contract is finished.