code: public void stopping() throws Exception {
  
  		// Update the HTTP service
  		this.logger.fine( "iPojo unregisters REST and icons servlets related to Roboconf's DM." );
  		if( this.httpService != null ) {
  			this.httpService.unregister( CONTEXT );
  
  		} else {
  			this.logger.fine( "The HTTP service is gone. The servlets were already unregistered." );
  		}
  
  		// Unregister the preference
  		if( this.manager != null ) {
  			this.manager.preferencesMngr().removeFromList( IPreferencesMngr.WEB_EXTENSIONS, CONTEXT );
  		}
  	}
docs: The method to use when dependencies are invalidated.
  @throws Exception in case of critical error