Bug 95217 [Commands] Remove experimental handlerSubmission element from the "org.eclipse.ui.commands" extension point
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/AbstractHandler.java
* instance.
	 * 
	 * @param handlerEvent
	 *            the event describing changes to this instance. Must not be
	 *            <code>null</code>.
	 */
	protected final void fireHandlerChanged(final HandlerEvent handlerEvent) {
		if (handlerEvent == null)
			throw new NullPointerException();
		if (handlerListeners != null)
			for (int i = 0; i < handlerListeners.size(); i++)
				((IHandlerListener) handlerListeners.get(i))
						.handlerChanged(handlerEvent);
	}
	/**
	 * Whether this handler is capable of executing at this time. Subclasses may
	 * override this method.
	 * 
	 * @return <code>true</code>
	 */
	public boolean isEnabled() {
		return true;
	}
	/**
	 * Whether this handler is capable of handling delegated responsibilities at
	 * this time. Subclasses may override this method.
	 * 
	 * @return <code>true</code>
	 */
	public boolean isHandled() {