credentialSets does not support creation of 'UserAssigned' resource identity

[tobiasholzner-whiteduck]

Describe the bug
I want to create a credentialSets resource with a UserAssigned identity using Bicep.

Bicep template: https://learn.microsoft.com/en-us/azure/templates/microsoft.containerregistry/registries/credentialsets?pivots=deployment-language-bicep

Error:

Resource type 'Microsoft.ContainerRegistry/registries/credentialSets' does not support creation of 'UserAssigned' resource identity. The supported types are 'SystemAssigned'

To Reproduce

resource dockerHubCredentialSetResource 'Microsoft.ContainerRegistry/registries/credentialSets@2023-01-01-preview' = {
  name: 'dockerhub'
  parent: acrResource
  identity: {
    type: 'UserAssigned'
    userAssignedIdentities: {
      'XXXX': {}
    }
  }
  properties: {
    authCredentials: [
      {
        name: 'dockerhub'
        passwordSecretIdentifier: 'https://XXXX'
        usernameSecretIdentifier: 'https://XXXX'
      }
    ]
    loginServer: 'docker.io'
  }
}

Expected behavior
The resource gets created

[ChrisSidebotham]

@JXavierMSFT - Can you provide an update?