Bug 31556 Export jar from Navigator view fails
(M5 build) In Navigator view (resource perspective), right-click on a src/ directory containing your sources, select export->jar file and the package selector opens with no resource selected (and finish button disabled); but it seems that the src/ dir is really selected, because if you re-select it in the window, it ends up with a "jar creation failed" and a lot of duplicate entries in the error log. If you try the same from the Projects view (Java browsing perspective), it works fine.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarPackageWizardPage.java
boolean removedOne= false;
		while (iter.hasNext()) {
			Object element= iter.next();
			Object parent;
			if (element instanceof IResource)
				parent= ((IResource)element).getParent();
			else if (element instanceof IJavaElement) {
				parent= ((IJavaElement)element).getParent();
				if (parent instanceof IPackageFragmentRoot) {
					IPackageFragmentRoot pkgRoot= (IPackageFragmentRoot)parent;
					try {
						if (pkgRoot.getCorrespondingResource() instanceof IProject)
							parent= pkgRoot.getJavaProject();
					} catch (JavaModelException ex) {
						
					}
				}
			}
			else {
				
				newList.add(element);
				continue;
			}
			if (element instanceof IJavaModel || ((!(parent instanceof IJavaModel)) && (elements.contains(parent) || javaElementResources.contains(parent))))
				removedOne= true;
			else
				newList.add(element);
		}
		if (removedOne)
			return removeContainedChildren(newList);