Cognito login issue

Hi, as per https://docs.aws.amazon.com/cognito-user-identity-pools/latest/APIReference/API_AdminCreateUser.html. the AdminCreateUser accepts username only up to 128 chars:

Username
The username for the user. Must be unique within the user pool. Must be a 
UTF-8 string between 1 and 128 characters. After the user is created, 
the username can't be changed.

Type: String

Length Constraints: Minimum length of 1. Maximum length of 128.

AFAIK, you cannot extend it.

Best, Didier