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
private TreeViewer fViewer;
	private Object fInput;
	private boolean fIsFlatLayout;
	private PackageFragmentProvider fPackageFragmentProvider= new PackageFragmentProvider();
	
	private int fPendingChanges;
	private PackageExplorerPart fPart;
	/**
	 * Creates a new content provider for Java elements.
	 */
	public PackageExplorerContentProvider(PackageExplorerPart part, boolean provideMembers, boolean provideWorkingCopy) {
		super(provideMembers, provideWorkingCopy);	
		fPart= part;
	}
	
	/* (non-Javadoc)
	 * Method declared on IElementChangedListener.
	 */
	public void elementChanged(final ElementChangedEvent event) {