credential method
Creates an OAuthCredential for SAML.
idToken Optional ID token.
accessToken Optional access token.
At least one token must be provided.
Returns an OAuthCredential instance.
Throws AssertionError if both tokens are null.
Example:
final cred = provider.credential(accessToken: 'saml_access_token');
Implementation
OAuthCredential credential({String? idToken, String? accessToken}) {
assert(accessToken != null || idToken != null, 'Tokens cannot be null!');
return OAuthCredential(providerId: providerId,
signInMethod: providerId, accessToken: accessToken,
idToken: idToken);
}