 expression must evaluate to a public
                method that takes a <code>ValueChangeEvent</code>
                parameter,
                with a return type of void, <span class="changed_added_2_0">or
                to a public method that takes no arguments with a return type
                of void. In the latter case, the method has no way of easily
                knowing what the new value is, but this can be useful in cases
                where a notification is needed that "this value
    