Bug 221768 [Viewers] Fix for bug 210747 causes NPE when parent is TreePath.EMPTY
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
}
		for (int column = 0; column < columnCount; column++) {
			ViewerColumn columnViewer = getViewerColumn(column);
			ViewerCell cellToUpdate = updateCell(viewerRowFromItem, column,
					element);
			
			if (isVirtual) {
				cellToUpdate = new ViewerCell(cellToUpdate.getViewerRow(), cellToUpdate.getColumnIndex(), element);
			}
			columnViewer.refresh(cellToUpdate);
			
			updateCell(null, 0, null);
			
			
			if (item.isDisposed()) {
				unmapElement(element, item);
				return;
			}
		}
	}
	/**
	 * Returns <code>true</code> if the given list and array of items refer to
	 * the same model elements. Order is unimportant.
	 * <p>
	 * This method is not intended to be overridden by subclasses.
	 * </p>
	 *
	 * @param items
	 *            the list of items
	 * @param current