Cloudformation SSL Certificate failed with error "Value null at 'domainValidationOptions.1.member.validationDomain' failed to satisfy constraint"

My cloudformation template keeps throwing the following error: Value null at 'domainValidationOptions.1.member.validationDomain' failed to satisfy constraint. What am I missing here? I am using a wildcard as the parameter (ex. *.domainname.ai).

SSLCertificate:
    Type: AWS::CertificateManager::Certificate
    Properties: 
      CertificateTransparencyLoggingPreference: DISABLED
      DomainName: 
        Ref: WildcardCertDomain
      DomainValidationOptions: 
        - DomainName: !Ref WildcardCertDomain
      ValidationMethod: DNS

I found the solution, you need to specify ValidationDomain: "example.com" and it must be the superdomain.

The final product should look like this:

SSLCertificate:
    Type: AWS::CertificateManager::Certificate
    Properties: 
      CertificateTransparencyLoggingPreference: DISABLED
      DomainName: 
        Ref: *.example.com
      DomainValidationOptions: 
        - DomainName: *.example.com
          ValidationDomain: "example.com"
      ValidationMethod: DNS