Bug 32664 Package Explorer: hierarchical layout and back-linking don't work allways together.
The following triggers it: - initially 'flat layout' is used, 'link with editor' is on or off - open a java file - use 'collapse all' in the package explorer - select 'hierarchical layout' - switch 'link with editor' on or off&on -> no back-linking
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerContentProvider.java
IJavaElementDelta[] affectedChildren= delta.getAffectedChildren();
		if (affectedChildren.length > 1) {
			
			if (element instanceof IPackageFragment) {
				IJavaElement parent= (IJavaElement)internalGetParent(element);
				
				
				if (element.equals(fInput)) {
					postRefresh(element);
				} else {
					postRefresh(parent);
				}
				return;
			}
			
			if (element instanceof IPackageFragmentRoot)
				postRefresh(skipProjectPackageFragmentRoot((IPackageFragmentRoot)element));
			else
				postRefresh(element);
			return;
		}
		processAffectedChildren(affectedChildren);
	}
	
	protected void processAffectedChildren(IJavaElementDelta[] affectedChildren) throws JavaModelException {
		for (int i= 0; i < affectedChildren.length; i++) {
			processDelta(affectedChildren[i]);
		}
	}