Bug 19278 jar source attachment: jar icon not refreshed [package explorer] [browsing]
F2 .a jar with no source attached .attach source the icon is still suggesting that no source is attached
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/browsing/JavaBrowsingContentProvider.java
* <p>
	 * Note: This method will return a working copy if the
	 * parent is a working copy. The super class implementation
	 * returns the original element instead.
	 * </p>
	 */	
	protected Object internalGetParent(Object element) {
		if (element instanceof IJavaProject) {
			return ((IJavaProject)element).getJavaModel();
		}
		
		if (element instanceof IResource) {
			IResource parent= ((IResource)element).getParent();
			Object jParent= JavaCore.create(parent);
			if (jParent != null) 
				return jParent;
			return parent;
		}
		
		
		if (element instanceof IPackageFragment) {
			IPackageFragmentRoot parent= (IPackageFragmentRoot)((IPackageFragment)element).getParent();
			return skipProjectPackageFragmentRoot(parent);
		}
		if (element instanceof IJavaElement)
			return ((IJavaElement)element).getParent();
		return null;
	}
}