code: @UiHandler("generateExceptionButton")
  	protected void onGenerateExceptionClicked(ClickEvent event) {
  		EmptyCommandRequest request = new EmptyCommandRequest();
  		GwtCommand command = new GwtCommand();
  		command.setCommandName("command.GetSimpleExceptionCommand");
  		command.setCommandRequest(request);
  		GeomajasServerExtension.getInstance().getCommandService()
  				.execute(command, new AbstractCommandCallback<CommandResponse>() {
  
  					@Override
  					public void execute(CommandResponse response) {
  						// don't do anything. An Exception will been thrown at
  						// server-side
  					}
  				});
  	}
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