Support generic list in DataFactoryExpression (Azure#32527)

* Support generic list

* PR fb

* update docs

* Support nullable values and reference type generics

* API

* Remove IReadOnlyList and clean up

* Update docs

* Fix deserialization of expression list

* Remove unnecessary AsEnumerable call

* Remove use of ChangeTrackingList as we do not leverage the IsCollectionDefined method anyway

* Remove unnecessary shared source; add target for net6.0

* API

* Fix tests

* Remove LiteralInternal

* PR fb

Author: JoshLove-msft

sdk/core/Azure.Core.Expressions.DataFactory/api/Azure.Core.Expressions.DataFactory.net461.cs

@@ -2,7 +2,7 @@ namespace Azure.Core.Expressions.DataFactory
 {
     public sealed partial class DataFactoryExpression<T>
     {
-        public DataFactoryExpression(T literal) { }
+        public DataFactoryExpression(T? literal) { }
         public bool HasLiteral { get { throw null; } }
         public T? Literal { get { throw null; } }
         [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]

sdk/core/Azure.Core.Expressions.DataFactory/api/Azure.Core.Expressions.DataFactory.net5.0.cs

@@ -2,7 +2,7 @@ namespace Azure.Core.Expressions.DataFactory
 {
     public sealed partial class DataFactoryExpression<T>
     {
-        public DataFactoryExpression(T literal) { }
+        public DataFactoryExpression(T? literal) { }
         public bool HasLiteral { get { throw null; } }
         public T? Literal { get { throw null; } }
         [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]

sdk/core/Azure.Core.Expressions.DataFactory/api/Azure.Core.Expressions.DataFactory.net6.0.cs

@@ -0,0 +1,16 @@
+namespace Azure.Core.Expressions.DataFactory
+{
+    public sealed partial class DataFactoryExpression<T>
+    {
+        public DataFactoryExpression(T? literal) { }
+        public bool HasLiteral { get { throw null; } }
+        public T? Literal { get { throw null; } }
+        [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
+        public override bool Equals(object? obj) { throw null; }
+        public static Azure.Core.Expressions.DataFactory.DataFactoryExpression<T> FromExpression(string expression) { throw null; }
+        [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
+        public override int GetHashCode() { throw null; }
+        public static implicit operator Azure.Core.Expressions.DataFactory.DataFactoryExpression<T> (T literal) { throw null; }
+        public override string? ToString() { throw null; }
+    }
+}

sdk/core/Azure.Core.Expressions.DataFactory/api/Azure.Core.Expressions.DataFactory.netcoreapp2.1.cs

@@ -2,7 +2,7 @@ namespace Azure.Core.Expressions.DataFactory
 {
     public sealed partial class DataFactoryExpression<T>
     {
-        public DataFactoryExpression(T literal) { }
+        public DataFactoryExpression(T? literal) { }
         public bool HasLiteral { get { throw null; } }
         public T? Literal { get { throw null; } }
         [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]

sdk/core/Azure.Core.Expressions.DataFactory/api/Azure.Core.Expressions.DataFactory.netstandard2.0.cs

@@ -2,7 +2,7 @@ namespace Azure.Core.Expressions.DataFactory
 {
     public sealed partial class DataFactoryExpression<T>
     {
-        public DataFactoryExpression(T literal) { }
+        public DataFactoryExpression(T? literal) { }
         public bool HasLiteral { get { throw null; } }
         public T? Literal { get { throw null; } }
         [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]

sdk/core/Azure.Core.Expressions.DataFactory/src/Azure.Core.Expressions.DataFactory.csproj

@@ -7,7 +7,7 @@
     <PackageTags>azure;datafactory</PackageTags>
     <Nullable>enable</Nullable>
     <DefineConstants>$(DefineConstants);AZURE_NULLABLE;HAS_INTERNALS_VISIBLE_CORE</DefineConstants>
-    <TargetFrameworks>$(RequiredTargetFrameworks);net461;netcoreapp2.1;net5.0</TargetFrameworks>
+    <TargetFrameworks>$(RequiredTargetFrameworks);net461;netcoreapp2.1;net5.0;net6.0</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <EnableClientSdkAnalyzers>true</EnableClientSdkAnalyzers>
     <EnableBannedApiAnalyzers>false</EnableBannedApiAnalyzers>
@@ -16,8 +16,6 @@
       to give customers time to migrate without losing perf optimizations
      -->
     <NoWarn>$(NoWarn);NETSDK1138</NoWarn>
-    <!--<IncludeGeneratorSharedCode>true</IncludeGeneratorSharedCode>
-    <IncludeOperationsSharedSource>true</IncludeOperationsSharedSource>-->
   </PropertyGroup>
 
   <ItemGroup>
@@ -26,9 +24,6 @@
 
   <ItemGroup>
     <Compile Include="$(AutoRestSharedCodeDirectory)IUtf8JsonSerializable.cs" LinkBase="Shared\AutoRest" />
-    <Compile Include="$(AutoRestSharedCodeDirectory)Optional.cs" LinkBase="Shared\AutoRest" />
-    <Compile Include="$(AutoRestSharedCodeDirectory)ChangeTrackingDictionary.cs" LinkBase="Shared\AutoRest" />
-    <Compile Include="$(AutoRestSharedCodeDirectory)ChangeTrackingList.cs" LinkBase="Shared\AutoRest" />
     <Compile Include="$(AutoRestSharedCodeDirectory)Utf8JsonWriterExtensions.cs" LinkBase="Shared\AutoRest" />
     <Compile Include="$(AutoRestSharedCodeDirectory)TypeFormatters.cs" LinkBase="Shared\AutoRest" />
     <Compile Include="$(AutoRestSharedCodeDirectory)JsonElementExtensions.cs" LinkBase="Shared\AutoRest" />

sdk/core/Azure.Core.Expressions.DataFactory/src/DataFactoryExpression.Serialization.cs

@@ -4,28 +4,30 @@
 using System;
 using System.ComponentModel;
 using System.Linq;
-using System.Security;
+using System.Text.Json.Serialization;
+using System.Collections.Generic;
 
 namespace Azure.Core.Expressions.DataFactory
 {
     /// <summary>
     /// A class representing either a primitive value or an expression.
     /// For details on DataFactoryExpressions see https://learn.microsoft.com/en-us/azure/data-factory/control-flow-expression-language-functions#expressions.
     /// </summary>
-    /// <typeparam name="T"> Can be one of <see cref="string"/>, <see cref="bool"/>, <see cref="int"/>, <see cref="double"/>, <see cref="Array"/>. </typeparam>
+    /// <typeparam name="T"> Can be one of <see cref="string"/>, <see cref="bool"/>, <see cref="int"/>, <see cref="double"/>, <see cref="Array"/>, or <see cref="IList{TElement}"/>.</typeparam>
 #pragma warning disable SA1649 // File name should match first type name
-    public sealed partial class DataFactoryExpression<T> : IUtf8JsonSerializable
+    [JsonConverter(typeof(DataFactoryExpressionJsonConverter))]
+    public sealed class DataFactoryExpression<T>
 #pragma warning restore SA1649 // File name should match first type name
     {
-        private string? _type;
-        private T? _literal;
-        private string? _expression;
+        internal string? Type { get; }
+        private readonly T? _literal;
+        internal string? Expression { get; }
 
         /// <summary>
         /// Initializes a new instance of DataFactoryExpression with a literal value.
         /// </summary>
         /// <param name="literal"> The literal value. </param>
-        public DataFactoryExpression(T literal)
+        public DataFactoryExpression(T? literal)
         {
             HasLiteral = true;
             _literal = literal;
@@ -52,8 +54,8 @@ public T? Literal
 
         internal DataFactoryExpression(string expression, string type)
         {
-            _type = type;
-            _expression = expression;
+            Type = type;
+            Expression = expression;
         }
 
         /// <inheritdoc/>
@@ -70,7 +72,7 @@ internal DataFactoryExpression(string expression, string type)
                     return _literal?.ToString();
                 }
             }
-            return _expression!;
+            return Expression!;
         }
 
         /// <summary>