code: public void registerUnregisteredNamespaces()
    {
      for (int i = 0; i < m_unregisteredExtensions.size(); i++)
      {
        String ns = (String)m_unregisteredExtensions.get(i);
        ExtensionNamespaceSupport extNsSpt = defineJavaNamespace(ns);
        if (extNsSpt != null)
          m_extensions.add(extNsSpt);
      }    
    }
docs: Attempt to register any unregistered extension namespaces.