code: public void setData(String key, String value) {
          QName qn = new QName("data-" + key);
          this.getOtherAttributes().put(qn, value);
      }
docs: <p>
  set data-* attribute
  </p>
  
  <pre>
  Div div = new Div();
  div.setData(&quot;foo&quot;, &quot;bar&quot;);
  // you get &lt;div data-foo=&quot;bar&quot;&gt;&lt;/div&gt;
  </pre>
  
  @param key
  data-"key"