Bug 92777 [Contributions] Spec clarification: ContributionItem.getParent() can return null
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ContributionItem.java
public void fill(Menu menu, int index) {
    }
    /**
     * The default implementation of this <code>IContributionItem</code>
     * method does nothing. Subclasses may override.
     */
    public void fill(ToolBar parent, int index) {
    }
    /**
     * The default implementation of this <code>IContributionItem</code>
     * method does nothing. Subclasses may override.
     * 
     * @since 3.0
     */
    public void fill(CoolBar parent, int index) {
    }
    /**
     * The default implementation of this <code>IContributionItem</code>
     * method does nothing. Subclasses may override.
     * 
     * @since 3.0
     */
    public void saveWidgetState() {
    }
    /* (non-Javadoc)
     * Method declared on IContributionItem.
     */
    public String getId() {
        return id;
    }