Add IList<T> and related APIs to JsonObject.

src/libraries/System.Text.Json/ref/System.Text.Json.cs

@@ -706,11 +706,11 @@ internal JsonNode() { }
         public System.Text.Json.Nodes.JsonValue AsValue() { throw null; }
         public System.Text.Json.Nodes.JsonNode DeepClone() { throw null; }
         public static bool DeepEquals(System.Text.Json.Nodes.JsonNode? node1, System.Text.Json.Nodes.JsonNode? node2) { throw null; }
-        public string GetPropertyName() { throw null; }
+        public int GetElementIndex() { throw null; }
         public string GetPath() { throw null; }
+        public string GetPropertyName() { throw null; }
+        public System.Text.Json.JsonValueKind GetValueKind() { throw null; }
         public virtual T GetValue<T>() { throw null; }
-        public JsonValueKind GetValueKind() { throw null; }
-        public int GetElementIndex() { throw null; }
         public static explicit operator bool (System.Text.Json.Nodes.JsonNode value) { throw null; }
         public static explicit operator byte (System.Text.Json.Nodes.JsonNode value) { throw null; }
         public static explicit operator char (System.Text.Json.Nodes.JsonNode value) { throw null; }
@@ -801,7 +801,7 @@ internal JsonNode() { }
         public static System.Threading.Tasks.Task<System.Text.Json.Nodes.JsonNode?> ParseAsync(System.IO.Stream utf8Json, System.Text.Json.Nodes.JsonNodeOptions? nodeOptions = default(System.Text.Json.Nodes.JsonNodeOptions?), System.Text.Json.JsonDocumentOptions documentOptions = default(System.Text.Json.JsonDocumentOptions), System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) { throw null; }
         [System.Diagnostics.CodeAnalysis.RequiresDynamicCodeAttribute("Creating JsonValue instances with non-primitive types requires generating code at runtime.")]
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Creating JsonValue instances with non-primitive types is not compatible with trimming. It can result in non-primitive types being serialized, which may have their members trimmed.")]
-        public void ReplaceWith<T>(T value) { throw null; }
+        public void ReplaceWith<T>(T value) { }
         public string ToJsonString(System.Text.Json.JsonSerializerOptions? options = null) { throw null; }
         public override string ToString() { throw null; }
         public abstract void WriteTo(System.Text.Json.Utf8JsonWriter writer, System.Text.Json.JsonSerializerOptions? options = null);
@@ -811,25 +811,35 @@ public partial struct JsonNodeOptions
         private int _dummyPrimitive;
         public bool PropertyNameCaseInsensitive { readonly get { throw null; } set { } }
     }
-    public sealed partial class JsonObject : System.Text.Json.Nodes.JsonNode, System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>, System.Collections.Generic.IDictionary<string, System.Text.Json.Nodes.JsonNode?>, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>, System.Collections.IEnumerable
+    public sealed partial class JsonObject : System.Text.Json.Nodes.JsonNode, System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>, System.Collections.Generic.IDictionary<string, System.Text.Json.Nodes.JsonNode?>, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>, System.Collections.Generic.IList<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>, System.Collections.IEnumerable
     {
         public JsonObject(System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>> properties, System.Text.Json.Nodes.JsonNodeOptions? options = default(System.Text.Json.Nodes.JsonNodeOptions?)) { }
         public JsonObject(System.Text.Json.Nodes.JsonNodeOptions? options = default(System.Text.Json.Nodes.JsonNodeOptions?)) { }
         public int Count { get { throw null; } }
         bool System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.IsReadOnly { get { throw null; } }
         System.Collections.Generic.ICollection<string> System.Collections.Generic.IDictionary<string, System.Text.Json.Nodes.JsonNode?>.Keys { get { throw null; } }
         System.Collections.Generic.ICollection<System.Text.Json.Nodes.JsonNode?> System.Collections.Generic.IDictionary<string, System.Text.Json.Nodes.JsonNode?>.Values { get { throw null; } }
+        System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?> System.Collections.Generic.IList<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.this[int index] { get { throw null; } set { } }
         public void Add(System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?> property) { }
         public void Add(string propertyName, System.Text.Json.Nodes.JsonNode? value) { }
         public void Clear() { }
         public bool ContainsKey(string propertyName) { throw null; }
         public static System.Text.Json.Nodes.JsonObject? Create(System.Text.Json.JsonElement element, System.Text.Json.Nodes.JsonNodeOptions? options = default(System.Text.Json.Nodes.JsonNodeOptions?)) { throw null; }
+        public System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?> GetAt(int index) { throw null; }
         public System.Collections.Generic.IEnumerator<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>> GetEnumerator() { throw null; }
+        public int IndexOf(string propertyName) { throw null; }
+        public void Insert(int index, string propertyName, System.Text.Json.Nodes.JsonNode? value) { }
         public bool Remove(string propertyName) { throw null; }
+        public void RemoveAt(int index) { }
+        public void SetAt(int index, string propertyName, System.Text.Json.Nodes.JsonNode? value) { }
+        public void SetAt(int index, System.Text.Json.Nodes.JsonNode? value) { }
         bool System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.Contains(System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode> item) { throw null; }
         void System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.CopyTo(System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode>[] array, int index) { }
         bool System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.Remove(System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode> item) { throw null; }
-        bool System.Collections.Generic.IDictionary<string, System.Text.Json.Nodes.JsonNode?>.TryGetValue(string propertyName, out System.Text.Json.Nodes.JsonNode? jsonNode) { throw null; }
+        bool System.Collections.Generic.IDictionary<string, System.Text.Json.Nodes.JsonNode?>.TryGetValue(string propertyName, out System.Text.Json.Nodes.JsonNode jsonNode) { throw null; }
+        int System.Collections.Generic.IList<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.IndexOf(System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode> item) { throw null; }
+        void System.Collections.Generic.IList<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.Insert(int index, System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode> item) { }
+        void System.Collections.Generic.IList<System.Collections.Generic.KeyValuePair<string, System.Text.Json.Nodes.JsonNode?>>.RemoveAt(int index) { }
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { throw null; }
         public bool TryGetPropertyValue(string propertyName, out System.Text.Json.Nodes.JsonNode? jsonNode) { throw null; }
         public override void WriteTo(System.Text.Json.Utf8JsonWriter writer, System.Text.Json.JsonSerializerOptions? options = null) { }

src/libraries/System.Text.Json/src/System.Text.Json.csproj

@@ -72,9 +72,6 @@ The System.Text.Json library is built-in as part of the shared framework in .NET
     <Compile Include="System\Text\Json\JsonHelpers.cs" />
     <Compile Include="System\Text\Json\JsonHelpers.Date.cs" />
     <Compile Include="System\Text\Json\JsonHelpers.Escaping.cs" />
-    <Compile Include="System\Text\Json\JsonPropertyDictionary.cs" />
-    <Compile Include="System\Text\Json\JsonPropertyDictionary.KeyCollection.cs" />
-    <Compile Include="System\Text\Json\JsonPropertyDictionary.ValueCollection.cs" />
     <Compile Include="System\Text\Json\JsonTokenType.cs" />
     <Compile Include="System\Text\Json\Nodes\JsonArray.cs" />
     <Compile Include="System\Text\Json\Nodes\JsonArray.IList.cs" />
@@ -85,6 +82,7 @@ The System.Text.Json library is built-in as part of the shared framework in .NET
     <Compile Include="System\Text\Json\Nodes\JsonNodeOptions.cs" />
     <Compile Include="System\Text\Json\Nodes\JsonObject.cs" />
     <Compile Include="System\Text\Json\Nodes\JsonObject.IDictionary.cs" />
+    <Compile Include="System\Text\Json\Nodes\JsonObject.IList.cs" />
     <Compile Include="System\Text\Json\Nodes\JsonValue.CreateOverloads.cs" />
     <Compile Include="System\Text\Json\Nodes\JsonValue.cs" />
     <Compile Include="System\Text\Json\Nodes\JsonValueOfTCustomized.cs" />
@@ -354,6 +352,16 @@ The System.Text.Json library is built-in as part of the shared framework in .NET
     <Compile Include="$(CoreLibSharedDir)System\Reflection\NullabilityInfoContext.cs" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp' or $([MSBuild]::VersionLessThan('$(TargetFrameworkVersion)', '9.0'))">
+    <Compile Include="System\Text\Json\JsonPropertyDictionary.cs" />
+    <Compile Include="System\Text\Json\JsonPropertyDictionary.KeyCollection.cs" />
+    <Compile Include="System\Text\Json\JsonPropertyDictionary.ValueCollection.cs" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' and $([MSBuild]::VersionGreaterThanOrEquals('$(TargetFrameworkVersion)', '9.0'))">
+    <Compile Include="System\Text\Json\JsonPropertyDictionary.Net90.cs" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' and $([MSBuild]::VersionGreaterThanOrEquals('$(TargetFrameworkVersion)', '7.0'))">
     <Compile Include="System\Text\Json\Serialization\Converters\Value\Int128Converter.cs" />
     <Compile Include="System\Text\Json\Serialization\Converters\Value\UInt128Converter.cs" />

src/libraries/System.Text.Json/src/System/Text/Json/JsonPropertyDictionary.KeyCollection.cs

@@ -8,13 +8,6 @@ namespace System.Text.Json
 {
     internal sealed partial class JsonPropertyDictionary<T>
     {
-        private KeyCollection? _keyCollection;
-
-        public IList<string> GetKeyCollection()
-        {
-            return _keyCollection ??= new KeyCollection(this);
-        }
-
         private sealed class KeyCollection : IList<string>
         {
             private readonly JsonPropertyDictionary<T> _parent;
@@ -30,7 +23,7 @@ public KeyCollection(JsonPropertyDictionary<T> jsonObject)
 
             public string this[int index]
             {
-                get => _parent.List[index].Key;
+                get => _parent.GetAt(index).Key;
                 set => throw ThrowHelper.GetNotSupportedException_CollectionIsReadOnly();
             }
 
@@ -46,7 +39,7 @@ IEnumerator IEnumerable.GetEnumerator()
 
             public void Clear() => ThrowHelper.ThrowNotSupportedException_CollectionIsReadOnly();
 
-            public bool Contains(string propertyName) => _parent.ContainsProperty(propertyName);
+            public bool Contains(string propertyName) => _parent.ContainsKey(propertyName);
 
             public void CopyTo(string[] propertyNameArray, int index)
             {

src/libraries/System.Text.Json/src/System/Text/Json/JsonPropertyDictionary.Net90.cs

@@ -0,0 +1,13 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Generic;
+
+namespace System.Text.Json
+{
+    /// <summary>
+    /// Defines an ordered dictionary for storing JSON property metadata.
+    /// </summary>
+    internal sealed class JsonPropertyDictionary<T>(StringComparer comparer, int capacity = 0)
+        : OrderedDictionary<string, T>(capacity, comparer);
+}

src/libraries/System.Text.Json/src/System/Text/Json/JsonPropertyDictionary.ValueCollection.cs

@@ -8,13 +8,6 @@ namespace System.Text.Json
 {
     internal sealed partial class JsonPropertyDictionary<T>
     {
-        private ValueCollection? _valueCollection;
-
-        public IList<T> GetValueCollection()
-        {
-            return _valueCollection ??= new ValueCollection(this);
-        }
-
         private sealed class ValueCollection : IList<T>
         {
             private readonly JsonPropertyDictionary<T> _parent;
@@ -30,7 +23,7 @@ public ValueCollection(JsonPropertyDictionary<T> jsonObject)
 
             public T this[int index]
             {
-                get => _parent.List[index].Value;
+                get => _parent.GetAt(index).Value;
                 set => throw ThrowHelper.GetNotSupportedException_CollectionIsReadOnly();
             }
 
@@ -42,13 +35,25 @@ IEnumerator IEnumerable.GetEnumerator()
                 }
             }
 
-            public void Add(T jsonNode) => ThrowHelper.ThrowNotSupportedException_CollectionIsReadOnly();
+            public void Add(T value) => ThrowHelper.ThrowNotSupportedException_CollectionIsReadOnly();
 
             public void Clear() => ThrowHelper.ThrowNotSupportedException_CollectionIsReadOnly();
 
-            public bool Contains(T jsonNode) => _parent.ContainsValue(jsonNode);
+            public bool Contains(T value)
+            {
+                EqualityComparer<T> comparer = _parent._valueComparer;
+                foreach (KeyValuePair<string, T> item in _parent._propertyList)
+                {
+                    if (comparer.Equals(item.Value, value))
+                    {
+                        return true;
+                    }
+                }
+
+                return false;
+            }
 
-            public void CopyTo(T[] nodeArray, int index)
+            public void CopyTo(T[] destination, int index)
             {
                 if (index < 0)
                 {
@@ -57,12 +62,12 @@ public void CopyTo(T[] nodeArray, int index)
 
                 foreach (KeyValuePair<string, T> item in _parent)
                 {
-                    if (index >= nodeArray.Length)
+                    if (index >= destination.Length)
                     {
-                        ThrowHelper.ThrowArgumentException_ArrayTooSmall(nameof(nodeArray));
+                        ThrowHelper.ThrowArgumentException_ArrayTooSmall(nameof(destination));
                     }
 
-                    nodeArray[index++] = item.Value;
+                    destination[index++] = item.Value;
                 }
             }
 
@@ -74,9 +79,9 @@ public IEnumerator<T> GetEnumerator()
                 }
             }
 
-            bool ICollection<T>.Remove(T node) => throw ThrowHelper.GetNotSupportedException_CollectionIsReadOnly();
+            bool ICollection<T>.Remove(T value) => throw ThrowHelper.GetNotSupportedException_CollectionIsReadOnly();
             public int IndexOf(T item) => throw ThrowHelper.GetNotSupportedException_CollectionIsReadOnly();
-            public void Insert(int index, T item) => throw ThrowHelper.GetNotSupportedException_CollectionIsReadOnly();
+            public void Insert(int index, T value) => throw ThrowHelper.GetNotSupportedException_CollectionIsReadOnly();
             public void RemoveAt(int index) => throw ThrowHelper.GetNotSupportedException_CollectionIsReadOnly();
         }
     }