SelectItem's values

Question

When traversing the source code for UISelectOne, I came across the following piece of code within the protected void validateValue(FacesContext context, Object value) method:

boolean found = SelectUtils.matchValue(getFacesContext(),
                                               this,
                                               value,
                                               new SelectItemsIterator(context, this),
                                               getConverter());

Consider the following declaration:

<h:selectOneRadio value="#{bean.pr}" converter="Conv" required="true" requiredMessage="msg">
    <f:selectItems value="#{bean.dates}" />
</h:selectOneRadio>

The converted value should be equal to one of the values I've populated the list with. The actual value has a different type than expected, so I get a validation error.

Question: Why is the converted value not consistent with the validated value?