Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/swt/ListUpdatableCollection.java
private final List list;
	private final String attribute;
	/**
	 * @param list
	 * @param attribute
	 */
	public ListUpdatableCollection(List list, String attribute) {
		this.list = list;
		
		
		if (attribute.equals(ViewersProperties.CONTENT)) {
			this.attribute = SWTProperties.ITEMS;
		} else {
			this.attribute = attribute;
		}
		
		if (this.attribute.equals(SWTProperties.ITEMS)) {
			
		} else {
			throw new IllegalArgumentException();
		}
	}
	public int computeSize() {
		return list.getItemCount();
	}
	public int addElement(Object value, int index) {