code: public void handlerDisappears( IMonitoringHandler handler ) {
  
  		// May happen if a target could not be instantiated
  		// (iPojo uses proxies). In this case, it results in a NPE here.
  		if( handler == null ) {
  			this.logger.info( "An invalid monitoring handler is removed." );
  		} else {
  			this.handlers.remove( handler );
  			this.logger.info( "Monitoring handler '" + handler.getName() + "' is not available anymore." );
  		}
  
  		listHandlers( this.handlers, this.logger );
  	}
docs: This method is invoked by iPojo every time a monitoring handler disappears.
  @param handler the disappearing monitoring handler