A standard AWS account ID (9+ digits).
An identity pool ID in the format REGION:GUID.
A set of optional name-value pairs that map provider names to provider tokens. The
available provider names for Logins are as follows:
Facebook: graph.facebook.com
Amazon Cognito user pool:
cognito-idp.,
for example, cognito-idp.us-east-1.amazonaws.com/us-east-1_123456789.
Google: accounts.google.com
Amazon: www.amazon.com
Twitter: api.twitter.com
Digits: www.digits.com
