mod_rest: Fix nested message stanzas in XEP-0297 containers It's all a bit awkward because it doesn't normally use the whole schema directly, but rather checks which stanza type is used and picks out that property as a schema. Which also prevents references from working.

<tr>
  <th>What is {x} {op} {y}?</th><td>
    <input name="captcha_challenge" type="hidden" value="{challenge}">
    <input name="captcha_reply" pattern="[0-9]+" required type="number">
  </td></tr>