THe main advantage of this solution is that it will be called on each rerendered whereas the other is not once href has been set.
Example API:
```
api.addNavigationBarItem({
name: "foo",
displayName: "Foo",
customHref: function(category, args) {
const router = api.container.lookup("service:router");
const queryParams = { bar: "1" };
return router.urlFor(router.currentRouteName, category, {
queryParams
});
}
});
```
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