Can an externally hosted domain be used with an application load balanced service?

[synapdk]

I've manually created and validated a certificate for a domain. I can import the certificate from the ARN, but the application load balanced service construct throws an error if a certificate and domain name are given without a hosted zone:

aws-cdk/packages/@aws-cdk/aws-ecs-patterns/lib/base/application-load-balanced-service-base.ts

Line 485 in cea1039

if (typeof props.domainZone === 'undefined') {

Is that really necessary? Do I have to create a fake hosted zone for it to work?