<h:message> errorClass attribute does nothing

When an error message is displayed after a conversion error, the <h:message> tag isn't rendered in the appropriate css class, as specified by the errorClass attribute.

For example:

<h:outputLabel id="datumLabel" for="datumInput">
<h:outputText value="#

"/>
</h:outputLabel>
<h:panelGrid columns="1" cellpadding="0" cellspacing="0">
<h:inputText id="datumInput"
size="10"
required="true"
value="#

"
>
<f:convertDateTime pattern="dd/MM/yyyy" />
</h:inputText>
<h:message id="datumMessage" for="datumInput" errorClass="error"
fatalClass="error" infoClass="message"
warnClass="message"/>
</h:panelGrid>

When an invalid date is entered here, the resulting HTML for the message looks like this:

<span id="body:_id4:datumMessage">ongeldige datum</span>

No trace of 'class="error"'

I have also tried the <x:message> tag, with the same result