As I'm using Maven and Gradle, over time my local artifact repositories have collected many related artifacts, e.g. junit-3.8.2.jar, junit-4.7.jar, junit-4.10.jar.
Now, whenever I open the "Open Type" dialog (e.g. by chording Ctrl+Shift+T), I get multiple entries for the type I'm looking up, e.g. JUnit's TestCase has 15+ entries for each version in both my local Maven and Gradle repositories.
As I'm mostly working with the latest releases of some artifact/library, I would like to filter this view for only the latest version (so as to remove visual cludder and to be more productive).
I think that you'll only see entries from a given jar in "Open Type" if there is a visible project with that type in its classpath - I didn't think just having it be in a repo would do that. Does this theory fit in your case? If so, Bananeweizen's answer MIGHT be relevant if it's workable for you to use working sets to hide the projects with the unwanted versions - and if they are hidden by working set exclusion. If they aren't hidden, and closing the projects that are pulling them in is an option, do that. In Eclipse use without repositories (without Maven, Gradle, etc.) closing projects definitely clears up this kind of problem - at least in the cases I've experienced.