code: private void addNullLabelExample() {
  		add(new WHeading(HeadingLevel.H2, "How to use accessible null WLabels"));
  		add(new ExplanatoryText("These examples shows how sometime a null WLabel is the right thing to do."
  				+ "\n This example uses a WFieldSet as the labelled component and it has its own \"label\"."));
  
  		// We want to add a WFieldSet to a WFieldLayout but without an extra label.
  		WFieldLayout fieldsFlat = new WFieldLayout();
  		fieldsFlat.setMargin(new Margin(null, null, Size.XL, null));
  		add(fieldsFlat);
  		WFieldSet fs = new WFieldSet("Do you like Bananas?");
  		fieldsFlat.addField((WLabel) null, fs);
  		// now add the WRadioButtons to the WFieldSet using an inner WFieldLayout
  		WFieldLayout innerLayout = new WFieldLayout(WFieldLayout.LAYOUT_STACKED);
  
  		// The content will be a group of WRadioButtons
  		RadioButtonGroup group1 = new RadioButtonGroup();
  		WRadioButton rb1 = group1.addRadioButton(1);
  		WRadioButton rb2 = group1.addRadioButton(2);
  		//make the labels for the radio buttons
  		WLabel rb1Label = new WLabel("", rb1);
  		WImage labelImage = new WImage("/image/success.png", "I still like bananas");
  		labelImage.setHtmlClass("wc-valign-bottom");
  		rb1Label.add(labelImage);
  		WLabel rb2Label = new WLabel("", rb2);
  		labelImage = new WImage("/image/error.png", "I still dislike bananas");
  		labelImage.setHtmlClass("wc-valign-bottom");
  		rb2Label.add(labelImage);
  		innerLayout.addField(rb1Label, rb1);
  		innerLayout.addField(rb2Label, rb2);
  		// add the content to the WFieldLayout - the order really doesn't matter.
  		fs.add(group1);
  		fs.add(innerLayout);
  	}
docs: Example of when and how to use a null WLabel.