HTML icons that worked fine in Vaadin 20 longer work in Vaadin 21

Question

In Vaadin 20 I could add an icon as a Java component:

add(new Icon("vaadin", "check));

or in HTML:

<iron-icon icon=vaadin:check></iron-icon>

Changing nothing but the Vaadin version, in Vaadin 21, the first shows an icon, the second is blank. I've gone through the Vaadin 21 documentation and there's nothing I can see about a formatting change, what's the deal?

Answer 1

iron-icon removed from Vaadin 21

I have no experience on this, but…

See this Answer by Jean-Christophe Gueriaud.

He explains that as part of the transition away from Polymer, iron-icon is no longer available in Vaadin 21 and later. The replacement is vaadin-icon.

One user reports that annotating @Uses(Icon.class) while replacing iron-icon with vaadin-icon in the template makes it work.

Perhaps the new doc pages Images and Icons and Vaadin Icons might help.