Okay thanks. I have done it and it works.
By the way, my plugin-directory also contains the jars of the old version (m1). Is there a way to configure eclipse to switch to different versions?
For example, in Mavens pom.xml, I can declare which version of a dependency I want to use. Is there a way to do that in eclipse? Would be really cool, if the plugin-directory is handled as a repo for eclipse the same as mavens repo.