Bug 7235 [Contributions] Need dispose() for action delegates
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ContributionItem.java
/**
	 * The identifier for this contribution item, of <code>null</code> if none.
	 */
	private String id = null;
	/**
	 * Indicates this item is visible in its manager; <code>true</code> 
	 * by default.
	 */
	private boolean visible = true;
    /**
     * The parent contribution manager for this item
     */
	private IContributionManager parent;
/**
 * Creates a contribution item with a <code>null</code> id.
 * Calls <code>this(String)</code> with <code>null</code>.
 */
protected ContributionItem() {
	this(null);
}
/**
 * Creates a contribution item with the given (optional) id.
 * The given id is used to find items in a contribution manager,