Bug 93360 [Viewers] getChild still used in indexForElement
indexForElement() in AbstractTreeViewer still uses getChild() and not getChildren(). This should probably also change to using getChildren() and do the same thing as insertionPosition().
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
if (data != null && data != element && equals(data, element)) {
            
            
            
            unmapElement(data, item);
            item.setData(element);
            mapElement(element, item);
        } else {
            
            super.associate(element, item);
        }
    }
    /**
     * Collapses all nodes of the viewer's tree, starting with the root. This
     * method is equivalent to <code>collapseToLevel(ALL_LEVELS)</code>.
     */
    public void collapseAll() {
        Object root = getRoot();
        if (root != null) {
            collapseToLevel(root, ALL_LEVELS);
        }
    }
    /**
     * Collapses the subtree rooted at the given element to the given level.
     * 
     * @param element
     *           the element
     * @param level
     *           non-negative level, or <code>ALL_LEVELS</code> to collapse
     *           all levels of the tree