[Cdn] Address the first review comments (Azure#28291)

* address first part comments

* address second part comments

* fix nullable issue

* update api

Author: Yao725

sdk/cdn/Azure.ResourceManager.Cdn/api/Azure.ResourceManager.Cdn.netstandard2.0.cs

@@ -22,7 +22,7 @@ public AfdCustomDomainData() { }
         public Azure.ResourceManager.Cdn.Models.DeploymentStatus? DeploymentStatus { get { throw null; } }
         public Azure.ResourceManager.Cdn.Models.DomainValidationState? DomainValidationState { get { throw null; } }
         public string HostName { get { throw null; } set { } }
-        public string PreValidatedCustomDomainResourceIdId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier PreValidatedCustomDomainResourceId { get { throw null; } set { } }
         public string ProfileName { get { throw null; } }
         public Azure.ResourceManager.Cdn.Models.AfdProvisioningState? ProvisioningState { get { throw null; } }
         public Azure.ResourceManager.Cdn.Models.AfdCustomDomainHttpsParameters TlsSettings { get { throw null; } set { } }
@@ -453,7 +453,7 @@ public partial class CdnEndpointData : Azure.ResourceManager.Models.TrackedResou
         public CdnEndpointData(Azure.Core.AzureLocation location) : base (default(Azure.Core.AzureLocation)) { }
         public System.Collections.Generic.IList<string> ContentTypesToCompress { get { throw null; } }
         public System.Collections.Generic.IReadOnlyList<Azure.ResourceManager.Cdn.CdnCustomDomainData> CustomDomains { get { throw null; } }
-        public string DefaultOriginGroupId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier DefaultOriginGroupId { get { throw null; } set { } }
         public Azure.ResourceManager.Cdn.Models.EndpointPropertiesUpdateParametersDeliveryPolicy DeliveryPolicy { get { throw null; } set { } }
         public System.Collections.Generic.IList<Azure.ResourceManager.Cdn.Models.GeoFilter> GeoFilters { get { throw null; } }
         public string HostName { get { throw null; } }
@@ -470,7 +470,7 @@ public CdnEndpointData(Azure.Core.AzureLocation location) : base (default(Azure.
         public Azure.ResourceManager.Cdn.Models.QueryStringCachingBehavior? QueryStringCachingBehavior { get { throw null; } set { } }
         public Azure.ResourceManager.Cdn.Models.EndpointResourceState? ResourceState { get { throw null; } }
         public System.Collections.Generic.IList<Azure.ResourceManager.Cdn.Models.UrlSigningKey> UrlSigningKeys { get { throw null; } set { } }
-        public string WebApplicationFirewallPolicyLinkId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier WebApplicationFirewallPolicyLinkId { get { throw null; } set { } }
     }
     public partial class CdnEndpointResource : Azure.ResourceManager.ArmResource
     {
@@ -581,7 +581,7 @@ public CdnOriginData() { }
         public string PrivateLinkAlias { get { throw null; } set { } }
         public string PrivateLinkApprovalMessage { get { throw null; } set { } }
         public string PrivateLinkLocation { get { throw null; } set { } }
-        public string PrivateLinkResourceId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier PrivateLinkResourceId { get { throw null; } set { } }
         public string ProvisioningState { get { throw null; } }
         public Azure.ResourceManager.Cdn.Models.OriginResourceState? ResourceState { get { throw null; } }
         public int? Weight { get { throw null; } set { } }
@@ -705,7 +705,7 @@ protected ProfileCollection() { }
     public partial class ProfileData : Azure.ResourceManager.Models.TrackedResourceData
     {
         public ProfileData(Azure.Core.AzureLocation location, Azure.ResourceManager.Cdn.Models.CdnSku sku) : base (default(Azure.Core.AzureLocation)) { }
-        public string FrontDoorId { get { throw null; } }
+        public System.Guid? FrontDoorId { get { throw null; } }
         public string Kind { get { throw null; } }
         public int? OriginResponseTimeoutSeconds { get { throw null; } set { } }
         public string ProvisioningState { get { throw null; } }
@@ -801,7 +801,7 @@ namespace Azure.ResourceManager.Cdn.Models
     public partial class ActivatedResourceReference
     {
         public ActivatedResourceReference() { }
-        public string Id { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier Id { get { throw null; } set { } }
         public bool? IsActive { get { throw null; } }
     }
     [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
@@ -828,13 +828,13 @@ public partial class AfdCustomDomainHttpsParameters
         public AfdCustomDomainHttpsParameters(Azure.ResourceManager.Cdn.Models.AfdCertificateType certificateType) { }
         public Azure.ResourceManager.Cdn.Models.AfdCertificateType CertificateType { get { throw null; } set { } }
         public Azure.ResourceManager.Cdn.Models.AfdMinimumTlsVersion? MinimumTlsVersion { get { throw null; } set { } }
-        public string SecretId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier SecretId { get { throw null; } set { } }
     }
     public partial class AfdCustomDomainPatch
     {
         public AfdCustomDomainPatch() { }
         public Azure.Core.ResourceIdentifier AzureDnsZoneId { get { throw null; } set { } }
-        public string PreValidatedCustomDomainResourceIdId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier PreValidatedCustomDomainResourceId { get { throw null; } set { } }
         public string ProfileName { get { throw null; } }
         public Azure.ResourceManager.Cdn.Models.AfdCustomDomainHttpsParameters TlsSettings { get { throw null; } set { } }
     }
@@ -1121,7 +1121,7 @@ public partial class CdnEndpointPatch
     {
         public CdnEndpointPatch() { }
         public System.Collections.Generic.IList<string> ContentTypesToCompress { get { throw null; } }
-        public string DefaultOriginGroupId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier DefaultOriginGroupId { get { throw null; } set { } }
         public Azure.ResourceManager.Cdn.Models.EndpointPropertiesUpdateParametersDeliveryPolicy DeliveryPolicy { get { throw null; } set { } }
         public System.Collections.Generic.IList<Azure.ResourceManager.Cdn.Models.GeoFilter> GeoFilters { get { throw null; } }
         public bool? IsCompressionEnabled { get { throw null; } set { } }
@@ -1134,7 +1134,7 @@ public CdnEndpointPatch() { }
         public Azure.ResourceManager.Cdn.Models.QueryStringCachingBehavior? QueryStringCachingBehavior { get { throw null; } set { } }
         public System.Collections.Generic.IDictionary<string, string> Tags { get { throw null; } }
         public System.Collections.Generic.IList<Azure.ResourceManager.Cdn.Models.UrlSigningKey> UrlSigningKeys { get { throw null; } set { } }
-        public string WebApplicationFirewallPolicyLinkId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier WebApplicationFirewallPolicyLinkId { get { throw null; } set { } }
     }
     public partial class CdnManagedHttpsOptions : Azure.ResourceManager.Cdn.Models.CustomDomainHttpsContent
     {
@@ -1161,7 +1161,7 @@ public CdnOriginPatch() { }
         public string PrivateLinkAlias { get { throw null; } set { } }
         public string PrivateLinkApprovalMessage { get { throw null; } set { } }
         public string PrivateLinkLocation { get { throw null; } set { } }
-        public string PrivateLinkResourceId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier PrivateLinkResourceId { get { throw null; } set { } }
         public int? Weight { get { throw null; } set { } }
     }
     public partial class CdnSku
@@ -1202,7 +1202,7 @@ public partial class CdnUsage
     {
         internal CdnUsage() { }
         public long CurrentValue { get { throw null; } }
-        public string Id { get { throw null; } }
+        public Azure.Core.ResourceIdentifier Id { get { throw null; } }
         public long Limit { get { throw null; } }
         public Azure.ResourceManager.Cdn.Models.UsageName Name { get { throw null; } }
         public Azure.ResourceManager.Cdn.Models.UsageUnit Unit { get { throw null; } }
@@ -1529,7 +1529,7 @@ public DeepCreatedOrigin(string name) { }
         public string PrivateLinkAlias { get { throw null; } set { } }
         public string PrivateLinkApprovalMessage { get { throw null; } set { } }
         public string PrivateLinkLocation { get { throw null; } set { } }
-        public string PrivateLinkResourceId { get { throw null; } set { } }
+        public Azure.Core.ResourceIdentifier PrivateLinkResourceId { get { throw null; } set { } }
         public int? Weight { get { throw null; } set { } }
     }
     public partial class DeepCreatedOriginGroup