this.listenerFilter = null; this.filter = filter;
	public ServiceTracker(BundleContext context, Filter filter,			ServiceTrackerCustomizer customizer) {		this.context = context;		this.trackReference = null;		this.trackClass = null;		this.listenerFilter = null;		this.filter = filter;		this.customizer = (customizer == null) ? this : customizer;		if ((context == null) || (filter == null)) { // we throw a NPE here			// to			// be consistent with the			// other constructors			throw new NullPointerException();		}	}