Bug 289409 [Viewers] ILazyTreePathContentProvider documentation request
I believe the JavaDoc for ILazyTreePathContentProvider#updateElement() should mention that the implementation can call TreeViewer#setHasChildren() instead of TreeViewer#setChildCount() if the content provider can more efficiently determine the has-children status than it can the actual number of children. This optimization was made possible by 156883. I think it needs to be advertised so clients can take advantage of it in their implementation of ILazyTreePathContentProvider#updateElement(). In fact, I think clients that use ILazyTreeContentProvider also have access to that optimization. If so, that JavaDoc should be updated, too.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ILazyTreePathContentProvider.java
* element at the given tree path, it should respond by calling
	 * {@link TreeViewer#setHasChildren(Object, boolean)}. The content provider
	 * may also choose to call {@link TreeViewer#setChildCount(Object, int)}
	 * instead if it knows the number of children.
	 * 
	 * <p>
	 * Intended as an optimization for when the viewer does not need the actual
	 * children. Clients may be able to implement this more efficiently than
	 * <code>updateChildCount</code>.
	 * </p>
	 * 
	 * @param path
	 *            The tree path for which up-to-date information about children
	 *            is needed
	 */
	public void updateHasChildren(TreePath path);
	/**
	 * Return the possible parent paths for the given element. An empty array
	 * can be returned if the paths cannot be computed. In this case the
	 * tree-structured viewer can't expand a given node correctly if requested.
	 * If the element is a potential child of the input of the viewer, an empty
	 * tree path should be an entry in the returned array.
	 * 
	 * @param element
	 *            the element
	 * @return the possible parent paths for the given element
	 */
	public TreePath[] getParents(Object element);
}