That image is not a resource image, but a mat-icon. I don't know whether the component has a property to select the default icon. I tried guessing at a few:
None of the above worked. It's possible that it does not have a property to set the initial default icon - but that seems unlikely? Either way, we'll have to wait for more documentation on what properties the component supports I suppose.
Thanks for this Yuliya. How can we go about finding this sort of thing out for ourselves in the new angular components? In the Extjs-based pages, it's easy to look at source to see what things can be done. However, with the angular components, plus everything being minified, it's very difficult to find where to look. Are there any tricks to using devtools to find the source of the components to look for this sort of thing (even if minified)?