title: Username cannot be of email format, since user pool is configured for email
body: <p>When I try sign up an user in AWS Cognito this error is returned in response.:</p>
  
  <p><a href="https://i.stack.imgur.com/vqDSG.png" rel="noreferrer"><img src="https://i.stack.imgur.com/vqDSG.png" alt="enter image description here"></a></p>
  
  <p>But, in my config the email field is an alias.:</p>
  
  <p><a href="https://i.stack.imgur.com/uhHQ7.png" rel="noreferrer"><img src="https://i.stack.imgur.com/uhHQ7.png" alt="enter image description here"></a></p>
  
  <p>How can I fix this? </p>