Launches the external IdP authorization flow for a Journey-scoped IdpCallback.
The native SDK handles the redirect internally — no JS-side deep-link listener
or journey.resume(uri) call is needed. On success, the callback's internal input
state is populated so journey.next({}) picks up the token.
Active Journey instance.
Optionaloptions: ExternalIdpAuthorizeOptionsOptional per-call authorize options (index).
A promise that resolves to the authorize result (token, additionalParameters).
Mutates the native SelectIdpCallback state for a Journey-scoped callback.
Must be called before journey.next({}) — calling next() with a SelectIdPCallback
entry directly always throws MissingIntegrationException / missingIntegration from
JourneyCallbackValueApplier on both platforms.
Active Journey instance.
The provider identifier chosen by the user (e.g. 'google').
Optionaloptions: ExternalIdpSelectOptionsOptional per-call select options (index).
Reusable client for external IdP operations in Journey flows.