The this can change what arguments are passed in the authentication URI in this method.
The default implementation sets some values too, namely "response_type", "client_id", "redirect_uri" and "login_hint", if available in
the source. These parameters are always provided, even when the interface implementer overrides this method.
The uri_query hash table expects both key and value to be newly allocated strings, which will be freed together with the
hash table or when the key is replaced.
| this | |
| source |
an associated Source |
| uri_query |
query for the URI to use |