title: GWT SuggestBox with placeholder attribute
body: <p>I'm looking for a way to specify the placeholder attribute inside a <code>&lt;g:SuggestBox&gt;</code> element, in GWT.
  I know that the <code>&lt;input&gt;</code> element allows to specify that attribute, but I decided to switch to the SuggestBox element instead of the input one.</p>
  
  <p>Can anyone help me?</p>