<moya xmlns="http://moyaproject.com"
      xmlns:let="http://moyaproject.com/let"
      xmlns:db="http://moyaproject.com/db"
      xmlns:preflight="http://moyaproject.com/preflight">

    <preflight:check>
        <preflight:warning if="not .app.settings.description">
            setting 'description' in [settings:${.app.name}] should not be empty
        </preflight:warning>
    </preflight:check>
</moya>