Description:
Hi, we have an issue with backend object when trying to set the hostname with subdomain that has single character in it. For example if we set the hostname to this subdomain backend.s.collector.example.com it will trigger this error

The Backend "backend" is invalid: spec.endpoints[0].fqdn.hostname: Invalid value: "backend.s.collector.example.com": spec.endpoints[0].fqdn.hostname in body should match '^[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9]))*$'

However when we set it to backend.staging.collector.example.com there's no issue

Is the regex is expected to not allow subdomain with single character?

Example manifest

apiVersion: gateway.envoyproxy.io/v1alpha1
kind: Backend
metadata:
  name: backend
  namespace: envoy-gateway-system
spec:
  endpoints:
  - fqdn:
      hostname: backend.s.collector.example.com
      port: 80