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
for (int i = 0; i < elements.length; i++) {
			for (int j = 0; j < items.length; j++) {
              if (items[j].getData().equals(elements[i])) {
              	
              	refresh(elements[i]);
                 return;
              }
			}
		  }
        }
		
		
		 
		
		int lastInsertion = 0;		
		if(items == null)
			items = getChildren(widget);			
		
		for (int i = 0; i < elements.length; i++) {
			Object element = elements[i];
			int index;
			if(sorter == null)
				index = items.length + i;
			else{
				lastInsertion = insertionPosition(items,sorter,lastInsertion, element);
				
				index = lastInsertion + i; 
				
				
				if (index >0 && index < items.length && items[index].getData().equals(element)) {