Bug 172019 [Viewers] Plus sign doesn't disappear when using deferred content providers
3.3 M4 Use a tree viewer with a content provider using IDeferredWorkbenchAdapter and DeferredTreeContentManager. When fetchDeferredChildren is call and no elements are reported to the element collector the plus sign of the node doesn't disappear. This work without problems under Windows and Mac/OS (e.g. the plus sign disappears).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
* expanded.
	 * </p>
	 * 
	 * @param level
	 *            non-negative level, or <code>ALL_LEVELS</code> to expand all
	 *            levels of the tree
	 */
	public void setAutoExpandLevel(int level) {
		expandToLevel = level;
	}
	/**
	 * The <code>AbstractTreeViewer</code> implementation of this method
	 * checks to ensure that the content provider is an
	 * <code>ITreeContentProvider</code>.
	 */
	public void setContentProvider(IContentProvider provider) {
		
		super.setContentProvider(provider);
	}
	protected void assertContentProviderType(IContentProvider provider) {
		Assert.isTrue(provider instanceof ITreeContentProvider
				|| provider instanceof ITreePathContentProvider);
	}
	/**
	 * Sets the expand state of the given item.
	 * 
	 * @param item
	 *            the item
	 * @param expand
	 *            the expand state of the item