Domain name starting with numeric character is invalid for Assisted Installer

Customer is trying to create RHOCP cluster with Domain name 123mydomain.com

In RedHat Hybrid Cloud Console customer is getting below error : 
~~~
Failed to update the cluster
DNS format mismatch: 123mydomain.com domain name is not valid
~~~

*** As per regex check as described in KCS - https://access.redhat.com/solutions/5517531
The domain name starting with numeric character is valid e.g. 123mydomain.com

Below is the RegeX check to find the domain name validity :
 [a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*')]

*** From the validations the assisted installer does as per : https://github.com/openshift/assisted-service/blob/master/pkg/validations/validations.go 

The below regexps are applied:
baseDomainRegex          = `^[a-z]([\-]*[a-z\d]+)+$`
dnsNameRegex             = `^([a-z]([\-]*[a-z\d]+)*\.)+[a-z\d]+([\-]*[a-z\d]+)+$`
wildCardDomainRegex      = `^(validateNoWildcardDNS\.).+\.?$`
hostnameRegex            = `^[a-z0-9][a-z0-9\-\.]{0,61}[a-z0-9]$`
installerArgsValuesRegex = `^[A-Za-z0-9@!#$%*()_+-=//.,";':{}\[\]]+$`
  
This means the domain name must start with a letter [a-z].

100%

1. Open RedHat Hybrid Cloud Console
2. Go to Clusters
3. Create Cluster
4. Go to Datacenter 
5. Under Assisted Installer -> Create Cluster
6. Enter Cluster Name mytestcluster and enter Domain Name 123mydomain.com
7. Click on Next

Domain name with numeric character first and then letters e.g. 123mydomain.com showing invalid in RedHat Hybrid Cloud Console Assisted Installer , throwing error :-
Failed to create new cluster
DNS format mismatch: 123mydomain.com domain name is not valid

Domain name with numeric character first and then letters e.g. 123mydomain.com must be valid in OpenShift RedHat Hybrid Cloud Console Assisted Installer