Processes message, adding all the necessary extra headers and parameters to ensure that it's correctly authenticated and
authorized under the given domain for the online service.
Basically, if a query is not processed by calling this method on it, it will be sent to the online service as if it's a query from a
non-logged-in user. Similarly, if the Authorizer isn't authenticated or authorized
(for domain), no changes will be made to the message.
domain may be null if the request doesn't require authorization.
This modifies message in place.
This method is thread safe.
| this | |
| domain |
the AuthorizationDomain the query falls under, or |
| message |
the query to process |