CloudFormation Serverless InviteMessageTemplate Configuration

From what I can tell, there is not a configuration specified in the Cognito User Pool specification that configures the Invitation Message Email. The 'Verification Message' can be configured here and whilst there is a document and field InviteMessageTemplate ref that suggests it would work for this, it doesn't actually appear to do so. Configuring this value results in an error:

Error:
UPDATE_FAILED: CognitoUserPool (AWS::Cognito::UserPool)
Properties validation failed for resource CognitoUserPool with message:
[#: extraneous key [InviteMessageTemplate] is not permitted]

Cloud formation will wipe out the existing template without being able to configure this value. Why isn't this value supported despite being in the documentation? How else can the invite message be configured through CloudFormation/Serverless deployments?