Hi Stefan,
your help has been precious. First of all, by restore the “eclipse.classpath.plusCpmfogiratopms << appServerRuntime” and then changing the exported flags of the existing entires in whenMerged, I fixed the problem that if a dependency was already in the build path, adding it a second time to set exported = true was “failing” because Buildship prevents a second addition of the same library (and hence the “exported” flag was not honoured for that dependency).
Secondly, I tried with a plain Java project requiring my Gradle project to check whether the exported flag on the single libraries within the “Project and External dependencies” works and indeed it works (i.e.: those libraries are in the dependent project build path). This means that the Tomcat Classpath composition code is actually borken.
I will open a bug against WTP as soon as I have a simple example workspace. By now, I must give up on trying to run this project in the WTP-managed Tomcat instance 