tapestry-core/src/test/app1/BadMixinIdDemo.tml

<t:border xmlns:t="http://tapestry.apache.org/schema/tapestry_5_0_0.xsd"
          xmlns:p="tapestry:parameter">

    <t:form>
        <t:textfield t:id="value" unknownmixinid.foo="bar"/>
    </t:form>

</t:border>