The problem is the value of the <phase>generate-sources</phase> tag.
Writing the »generate-sources« completely in lower case makes the build working (e.g. when I enter »mvn install« from commandline). But in eclipse I got an error:
Plugin execution not covered by lifecycle configuration: org.apache.maven.plugins:maven-antrun-plugin:1.7:run (execution: default, phase: generate-sources)
I got this error message in different places like:
* Maven POM Editor
* Xml Editor
* Problems View
The error message disappears when I simply turn the value of <phase> to »Generate-sources« or »Generate-Sources«. But when doing this, my antrun will not longer called during the build. (No warnings or errors, just the same behaviour as I remove the complete plugin section (<plugin> <artifactId>maven-antrun-plugin</artifactId> ... </plugin>) from my pom.xml).