This is from the documentation

Identity = new AzureNative.ContainerService.Inputs.ManagedClusterIdentityArgs
            {
                Type = "UserAssigned",
                UserAssignedIdentities = 
                {
                    { "/subscriptions/subid1/resourceGroups/rgName1/providers/Microsoft.ManagedIdentity/userAssignedIdentities/identity1",  },
                },
            },