JSF2 ignores empty alt attribute

I have a jsf snippet:

<ui:composition xmlns="http://www.w3.org/1999/xhtml" xmlns:ui=开发者_如何学编程"http://java.sun.com/jsf/facelets">
<!-- Yandex.Metrika -->
<img src="//mc.yandex.ru/watch/xxx" alt=""/>
<!-- /Yandex.Metrika -->
</ui:composition>

But when I use it, web-client get HTML page whithout empty alt attribute in img element:

<!-- Yandex.Metrika -->
<img src="//mc.yandex.ru/watch/xxx" />
<!-- /Yandex.Metrika -->

As result my document has validation error (

How can I solve this problem?

You could use the JSF graphicImage component, which does render the empty alt attribute.

For Example:

<h:graphicImage value="#{resource['images:image1.png']}" alt="" />

or

<h:graphicImage value="http://somedomain.com/somecontext/xxx/image1.png" alt="" />

Not sure if that is a bug in JSF2 (JSF1.2 preserves empty attributes). To 'workaround' that in JSF2, wrap code by f:verbatim, like this:

<f:verbatim>
   <img src="//mc.yandex.ru/watch/xxx" alt=""/>
</f:verbatim>