Schedule an experiment. The in design campaign will be converted into a real campaign (called the experiment campaign) that will begin serving ads if successfully created. The experiment is scheduled immediately with status INITIALIZING. This method returns a long running operation that tracks the forking of the in design campaign. If the forking fails, a list of errors can be retrieved using the ListExperimentAsyncErrors method. The operation's metadata will be a string containing the resource name of the created experiment. List of thrown errors: AuthenticationError AuthorizationError ExperimentError DatabaseError DateError DateRangeError FieldError HeaderError InternalError QuotaError RangeError RequestError