code: @Override
      public XmlStringBuilder toXML(org.jivesoftware.smack.packet.XmlEnvironment enclosingNamespace) {
          XmlStringBuilder xml = new XmlStringBuilder(this);
          xml.attribute("hash", hash).attribute("node", node).attribute("ver", ver);
          xml.closeEmptyElement();
          return xml;
      }
docs: {@inheritDoc}.
  
  <pre>
  &lt;c xmlns='http://jabber.org/protocol/caps'
  hash='sha-1'
  node='http://code.google.com/p/exodus'
  ver='QgayPKawpkPSDYmwT/WM94uAlu0='/&gt;
  </pre>