ts returned from this
 call are safe to cache.
 <p>
 Note that the output of <code>freeze</code> may not be identical to the parent object, but should
 be equal. In other words:

 <pre>
 <code>
 Freezable f1 = new Freezable();
 Freezable f2 = f1.freeze();
 f1 == f2 may not be true.
 f1.equals(f2) will be true.
 </code>
 </pre></p></div>
  <div class="jd-tagdata">
      <h5 class="jd-tagtitle">Returns</h5>
      <ul class="nolist"><li>A concrete implementation of the data object.
</li></ul>
  </div>

    </d