get_auth_message_template
Returns the auth message template that is needed to authorize a certain operation, given its arguments. It will either use the one defined in auth_handler.message_formatter
, or create a default one from the args if the former does not exist.
Throws if the auth handler for op_name
cannot be found.
Parameters
op_name
the name of the operation to authorize
op_args
the arguments passed to the operation