title: GWT CELLTABLE : How to add column in celltable which is combination of non-editable text + hyperlink
body: <p>I want to add link in my celltable's column i.e"validationStatus"
  some values are "valid" as well as "invalid"
  when value is invalid then I want to make invalid as link (How to ?)
  &amp; when value is valid then I want to make it as text</p>
  
  <p>How to add link in celltables particular column ? </p>
  
  <p>I want to add Column which is combination of non-editable text(valid) + hyperlink (invalid)if any.</p>