This is my first take at #622 just to be sure I’m not headed in a completely wrong direction.
This first small step makes that a Fragment is no longer based on a plain string for the uri part, but on AllowedUrl.
That means that if it is set, it is a valid Url.
This required changes on tests scattered arround, where it was like
foo not being a valid uri, it required changing it to
Is this the desired behaviour? Isn’t there a risk to break things where
foo#bar might have been valid?