How to configure 'Pre Token Generation' trigger via CloudFormation?

Pre Token Generation trigger: This Lambda trigger allows you to customize an identity token before it is generated: https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-lambda-pre-token-generation.html

I am looking for a way to configure this trigger via CloudFormation. Something like:

UserPool:
  Type: AWS::Cognito::UserPool
  Properties:
    LambdaConfig:
      # Next line does not work:
      PreTokenGeneration: [lambda ARN]

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-cognito-userpool-lambdaconfig.html

I found docs for other triggers, but this one is missing. Is this a missing feature or just not documented?