title: how to add an image to a cell in cellTable in GWT
body: <p>I want to add an image in a cell in the CellTable. After reading the documentation, this is what I did,</p>
  
  <pre><code>Column&lt;Contact, String&gt; imageColumn = new Column&lt;Contact, String&gt;(new ImageCell()) {
      @Override
      public String getValue(Contact object) {
          return "contact.jpg";
      }
    };
  table.addColumn(imageColumn, "");
  </code></pre>
  
  <p>Well, there's an empty column in the table now and no image in it. Am I doing something wrong here? Any suggestion is appreciated. Thank you.</p>