[Bug Report] AWS::Cognito::UserPoolRiskConfigurationAttachment has inconsistent validation for ClientId property

Your documentation here:

https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-cognito-userpoolriskconfigurationattachment.html#cfn-cognito-userpoolriskconfigurationattachment-clientid

.. says that the ClientId property is optional in its description:

"The app client where this configuration is applied. When this parameter isn't present, the risk configuration applies to all user pool app clients that don't have client-level settings."

However, the property is marked as "Required: Yes" in CloudFormation and the validation ensures it is non-empty.

Plz fix