Add IsAzureArm to distinguish MPG and DPG

eng/Packages.Data.props

@@ -254,7 +254,7 @@
   </ItemGroup>
 
   <ItemGroup Condition="'$(IsGeneratorLibrary)' == 'true'">
-    <PackageReference Update="Microsoft.Generator.CSharp.ClientModel" Version="1.0.0-alpha.20241121.2" />
+    <PackageReference Update="Microsoft.Generator.CSharp.ClientModel" Version="1.0.0-alpha.20241128.1" />
   </ItemGroup>
 
   <!--

eng/packages/http-client-csharp/emitter/src/emitter.ts

@@ -5,11 +5,14 @@ import { EmitContext } from "@typespec/compiler";
 
 import {
   $onEmit as $OnMGCEmit,
-  NetEmitterOptions
+  NetEmitterOptions,
+  setSDKContextOptions
 } from "@typespec/http-client-csharp";
+import { azureSDKContextOptions } from "./sdk-context-options.js";
 
 export async function $onEmit(context: EmitContext<NetEmitterOptions>) {
   context.options["plugin-name"] = "AzureClientPlugin";
   context.options["emitter-extension-path"] = import.meta.url;
+  setSDKContextOptions(azureSDKContextOptions);
   await $OnMGCEmit(context);
 }

eng/packages/http-client-csharp/emitter/src/sdk-context-options.ts

@@ -0,0 +1,12 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+import { CreateSdkContextOptions } from "@azure-tools/typespec-client-generator-core";
+
+export const azureSDKContextOptions: CreateSdkContextOptions = {
+    versioning: {},
+    additionalDecorators: [
+        "Azure\\.ClientGenerator\\.Core\\.@useSystemTextJsonConverter",
+        "Azure\\.ResourceManager\\.@armProviderNamespace"
+    ]
+};

eng/packages/http-client-csharp/generator/Azure.Generator/src/AzureClientPlugin.cs

@@ -27,6 +27,10 @@ public class AzureClientPlugin : ClientModelPlugin
     /// <inheritdoc/>
     public override AzureOutputLibrary OutputLibrary => _azureOutputLibrary ??= new();
 
+    private AzureInputLibrary? _azureInputLibrary;
+    /// <inheritdoc/>
+    public override AzureInputLibrary InputLibrary => _azureInputLibrary ??= new(Instance.Configuration.OutputDirectory);
+
     /// <summary>
     /// The Azure client plugin to generate the Azure client SDK.
     /// </summary>

eng/packages/http-client-csharp/generator/Azure.Generator/src/AzureInputLibrary.cs

@@ -0,0 +1,23 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using Microsoft.Generator.CSharp.Input;
+using System;
+using System.Linq;
+
+namespace Azure.Generator
+{
+    /// <inheritdoc/>
+    public class AzureInputLibrary : InputLibrary
+    {
+        /// <inheritdoc/>
+        public AzureInputLibrary(string codeModelPath) : base(codeModelPath)
+        {
+        }
+
+        /// <summary>
+        /// Identify if the input is generated for Azure ARM.
+        /// </summary>
+        internal Lazy<bool> IsAzureArm => new Lazy<bool>(() => InputNamespace.Clients.Any(c => c.Decorators.Any(d => d.Name.Equals("Azure.ResourceManager.@armProviderNamespace"))));
+    }
+}

eng/packages/http-client-csharp/generator/Azure.Generator/test/TestHelpers/MockHelpers.cs

@@ -47,7 +47,7 @@ public static Mock<AzureClientPlugin> LoadMockPlugin(
                 inputNsModels,
                 inputNsClients,
                 inputNsAuth);
-            var mockInputLibrary = new Mock<InputLibrary>(_configFilePath);
+            var mockInputLibrary = new Mock<AzureInputLibrary>(_configFilePath);
             mockInputLibrary.Setup(p => p.InputNamespace).Returns(mockInputNs.Object);
 
             if (createCSharpTypeCore is not null)