Add missing APIs to contract customization

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

@@ -364,6 +364,9 @@ public JsonSerializerOptions(System.Text.Json.JsonSerializerOptions options) { }
         [System.Diagnostics.CodeAnalysis.RequiresDynamicCodeAttribute("Getting a converter for a type may require reflection which depends on runtime code generation.")]
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("Getting a converter for a type may require reflection which depends on unreferenced code.")]
         public System.Text.Json.Serialization.JsonConverter GetConverter(System.Type typeToConvert) { throw null; }
+        [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCode("Getting a metadata for a type may require reflection which depends on unreferenced code.")]
+        [System.Diagnostics.CodeAnalysis.RequiresDynamicCode("Getting a metadata for a type may require reflection which depends on runtime code generation.")]
+        public System.Text.Json.Serialization.Metadata.JsonTypeInfo GetTypeInfo(System.Type type) { throw null; }
     }
     public enum JsonTokenType : byte
     {
@@ -1148,11 +1151,14 @@ public JsonPolymorphismOptions() { }
     public abstract partial class JsonPropertyInfo
     {
         internal JsonPropertyInfo() { }
+        public System.Reflection.ICustomAttributeProvider? AttributeProvider { get { throw null; } set { } }
         public System.Text.Json.Serialization.JsonConverter? CustomConverter { get { throw null; } set { } }
         public System.Func<object, object?>? Get { get { throw null; } set { } }
+        public bool IsExtensionData { get { throw null; } set { } }
         public string Name { get { throw null; } set { } }
         public System.Text.Json.Serialization.JsonNumberHandling? NumberHandling { get { throw null; } set { } }
         public System.Text.Json.JsonSerializerOptions Options { get { throw null; } }
+        public int Order { get { throw null; } set { } }
         public System.Type PropertyType { get { throw null; } }
         public System.Action<object, object?>? Set { get { throw null; } set { } }
         public System.Func<object, object?, bool>? ShouldSerialize { get { throw null; } set { } }
@@ -1183,6 +1189,10 @@ internal JsonTypeInfo() { }
         public System.Func<object>? CreateObject { get { throw null; } set { } }
         public System.Text.Json.Serialization.Metadata.JsonTypeInfoKind Kind { get { throw null; } }
         public System.Text.Json.Serialization.JsonNumberHandling? NumberHandling { get { throw null; } set { } }
+        public System.Action<object>? OnDeserialized { get { throw null; } set { } }
+        public System.Action<object>? OnDeserializing { get { throw null; } set { } }
+        public System.Action<object>? OnSerialized { get { throw null; } set { } }
+        public System.Action<object>? OnSerializing { get { throw null; } set { } }
         public System.Text.Json.JsonSerializerOptions Options { get { throw null; } }
         public System.Text.Json.Serialization.Metadata.JsonPolymorphismOptions? PolymorphismOptions { get { throw null; } set { } }
         public System.Collections.Generic.IList<System.Text.Json.Serialization.Metadata.JsonPropertyInfo> Properties { get { throw null; } }

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/ConfigurationList.cs

@@ -13,7 +13,7 @@ namespace System.Text.Json.Serialization
     /// </summary>
     internal abstract class ConfigurationList<TItem> : IList<TItem>
     {
-        private readonly List<TItem> _list;
+        protected readonly List<TItem> _list;
 
         public ConfigurationList(IList<TItem>? source = null)
         {

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializer.Helpers.cs

@@ -22,7 +22,7 @@ private static JsonTypeInfo GetTypeInfo(JsonSerializerOptions? options, Type run
             options ??= JsonSerializerOptions.Default;
             options.InitializeForReflectionSerializer();
 
-            return options.GetJsonTypeInfoForRootType(runtimeType);
+            return options.GetTypeInfoForRootType(runtimeType);
         }
 
         private static JsonTypeInfo GetTypeInfo(JsonSerializerContext context, Type type)

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/JsonSerializerOptions.Caching.cs

@@ -23,10 +23,55 @@ public sealed partial class JsonSerializerOptions
         // Simple LRU cache for the public (de)serialize entry points that avoid some lookups in _cachingContext.
         private volatile JsonTypeInfo? _lastTypeInfo;
 
+        /// <summary>
+        /// Gets the <see cref="JsonTypeInfo"/> contract metadata resolved by the current <see cref="JsonSerializerOptions"/> instance.
+        /// </summary>
+        /// <param name="type">The type to resolve contract metadata for.</param>
+        /// <returns>The contract metadata resolved for <paramref name="type"/>.</returns>
+        /// <remarks>
+        /// Returned metadata can be downcast to <see cref="JsonTypeInfo{T}"/> and used with the relevant <see cref="JsonSerializer"/> overloads.
+        ///
+        /// If the <see cref="JsonSerializerOptions"/> instance is locked for modification, the method will return a cached instance for the metadata.
+        /// </remarks>
+        [RequiresUnreferencedCode("Getting a metadata for a type may require reflection which depends on unreferenced code.")]
+        [RequiresDynamicCode("Getting a metadata for a type may require reflection which depends on runtime code generation.")]
+        public JsonTypeInfo GetTypeInfo(Type type)
+        {
+            if (type is null)
+            {
+                ThrowHelper.ThrowArgumentNullException(nameof(type));
+            }
+
+            if (JsonTypeInfo.IsInvalidForSerialization(type))
+            {
+                ThrowHelper.ThrowArgumentException_CannotSerializeInvalidType(nameof(type), type, null, null);
+            }
+
+            _typeInfoResolver ??= DefaultJsonTypeInfoResolver.RootDefaultInstance();
+
+            JsonTypeInfo? typeInfo;
+            if (IsLockedInstance)
+            {
+                typeInfo = GetCachingContext()?.GetOrAddJsonTypeInfo(type);
+                typeInfo?.EnsureConfigured();
+            }
+            else
+            {
+                typeInfo = GetTypeInfoNoCaching(type);
+            }
+
+            if (typeInfo is null)
+            {
+                ThrowHelper.ThrowNotSupportedException_NoMetadataForType(type);
+            }
+
+            return typeInfo;
+        }
+
         /// <summary>
         /// This method returns configured non-null JsonTypeInfo
         /// </summary>
-        internal JsonTypeInfo GetJsonTypeInfoCached(Type type)
+        internal JsonTypeInfo GetTypeInfoCached(Type type)
         {
             JsonTypeInfo? typeInfo = null;
 
@@ -45,7 +90,7 @@ internal JsonTypeInfo GetJsonTypeInfoCached(Type type)
             return typeInfo;
         }
 
-        internal bool TryGetJsonTypeInfoCached(Type type, [NotNullWhen(true)] out JsonTypeInfo? typeInfo)
+        internal bool TryGetTypeInfoCached(Type type, [NotNullWhen(true)] out JsonTypeInfo? typeInfo)
         {
             if (_cachingContext == null)
             {
@@ -61,13 +106,13 @@ internal bool TryGetJsonTypeInfoCached(Type type, [NotNullWhen(true)] out JsonTy
         /// This has an LRU cache that is intended only for public API calls that specify the root type.
         /// </summary>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal JsonTypeInfo GetJsonTypeInfoForRootType(Type type)
+        internal JsonTypeInfo GetTypeInfoForRootType(Type type)
         {
             JsonTypeInfo? jsonTypeInfo = _lastTypeInfo;
 
             if (jsonTypeInfo?.Type != type)
             {
-                jsonTypeInfo = GetJsonTypeInfoCached(type);
+                jsonTypeInfo = GetTypeInfoCached(type);
                 _lastTypeInfo = jsonTypeInfo;
             }
 

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/DefaultJsonTypeInfoResolver.Converters.cs

@@ -144,7 +144,7 @@ internal static JsonConverter GetConverterForMember(
             JsonConverterAttribute? converterAttribute = memberInfo.GetUniqueCustomAttribute<JsonConverterAttribute>(inherit: false);
             customConverter = converterAttribute is null ? null : GetConverterFromAttribute(converterAttribute, typeToConvert, memberInfo, options);
 
-            return options.TryGetJsonTypeInfoCached(typeToConvert, out JsonTypeInfo? typeInfo)
+            return options.TryGetTypeInfoCached(typeToConvert, out JsonTypeInfo? typeInfo)
                 ? typeInfo.Converter
                 : GetConverterForType(typeToConvert, options);
         }

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/JsonParameterInfo.cs

@@ -39,7 +39,7 @@ public JsonTypeInfo JsonTypeInfo
             {
                 Debug.Assert(Options != null);
                 Debug.Assert(ShouldDeserialize);
-                return _jsonTypeInfo ??= Options.GetJsonTypeInfoCached(PropertyType);
+                return _jsonTypeInfo ??= Options.GetTypeInfoCached(PropertyType);
             }
             set
             {
@@ -97,7 +97,7 @@ public static JsonParameterInfo CreateIgnoredParameterPlaceholder(
                 Type parameterType = parameterInfo.ParameterType;
 
                 DefaultValueHolder holder;
-                if (matchingProperty.Options.TryGetJsonTypeInfoCached(parameterType, out JsonTypeInfo? typeInfo))
+                if (matchingProperty.Options.TryGetTypeInfoCached(parameterType, out JsonTypeInfo? typeInfo))
                 {
                     holder = typeInfo.DefaultValueHolder;
                 }

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/JsonPropertyInfo.cs

@@ -143,7 +143,7 @@ internal JsonIgnoreCondition? IgnoreCondition
         /// Setting a custom attribute provider will have no impact on the contract model,
         /// but serves as metadata for downstream contract modifiers.
         /// </remarks>
-        internal ICustomAttributeProvider? AttributeProvider
+        public ICustomAttributeProvider? AttributeProvider
         {
             get => _attributeProvider;
             set
@@ -166,7 +166,7 @@ internal ICustomAttributeProvider? AttributeProvider
         /// Properties annotated with <see cref="JsonExtensionDataAttribute"/>
         /// will appear here when using <see cref="DefaultJsonTypeInfoResolver"/> or <see cref="JsonSerializerContext"/>.
         /// </remarks>
-        internal bool IsExtensionData
+        public bool IsExtensionData
         {
             get => _isExtensionDataProperty;
             set
@@ -631,7 +631,7 @@ public string Name
         /// When using <see cref="DefaultJsonTypeInfoResolver"/>, properties annotated
         /// with the <see cref="JsonPropertyOrderAttribute"/> will map to this value.
         /// </remarks>
-        internal int Order
+        public int Order
         {
             get => _order;
             set
@@ -757,7 +757,7 @@ internal JsonTypeInfo JsonTypeInfo
                 else
                 {
                     // GetOrAddJsonTypeInfo already ensures it's configured.
-                    _jsonTypeInfo = Options.GetJsonTypeInfoCached(PropertyType);
+                    _jsonTypeInfo = Options.GetTypeInfoCached(PropertyType);
                 }
 
                 return _jsonTypeInfo;

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/JsonTypeInfo.cs

@@ -53,7 +53,7 @@ public Func<object>? CreateObject
         /// <remarks>
         /// Types implementing <see cref="IJsonOnSerializing"/> will map to this callback.
         /// </remarks>
-        internal Action<object>? OnSerializing
+        public Action<object>? OnSerializing
         {
             get => _onSerializing;
             set
@@ -75,7 +75,7 @@ internal Action<object>? OnSerializing
         /// <remarks>
         /// Types implementing <see cref="IJsonOnSerialized"/> will map to this callback.
         /// </remarks>
-        internal Action<object>? OnSerialized
+        public Action<object>? OnSerialized
         {
             get => _onSerialized;
             set
@@ -97,7 +97,7 @@ internal Action<object>? OnSerialized
         /// <remarks>
         /// Types implementing <see cref="IJsonOnSerializing"/> will map to this callback.
         /// </remarks>
-        internal Action<object>? OnDeserializing
+        public Action<object>? OnDeserializing
         {
             get => _onDeserializing;
             set
@@ -119,7 +119,7 @@ internal Action<object>? OnDeserializing
         /// <remarks>
         /// Types implementing <see cref="IJsonOnDeserialized"/> will map to this callback.
         /// </remarks>
-        internal Action<object>? OnDeserialized
+        public Action<object>? OnDeserialized
         {
             get => _onDeserialized;
             set
@@ -226,7 +226,7 @@ internal JsonTypeInfo? ElementTypeInfo
                     {
                         // GetOrAddJsonTypeInfo already ensures JsonTypeInfo is configured
                         // also see comment on JsonPropertyInfo.JsonTypeInfo
-                        _elementTypeInfo = Options.GetJsonTypeInfoCached(ElementType);
+                        _elementTypeInfo = Options.GetTypeInfoCached(ElementType);
                     }
                 }
                 else
@@ -268,7 +268,7 @@ internal JsonTypeInfo? KeyTypeInfo
 
                         // GetOrAddJsonTypeInfo already ensures JsonTypeInfo is configured
                         // also see comment on JsonPropertyInfo.JsonTypeInfo
-                        _keyTypeInfo = Options.GetJsonTypeInfoCached(KeyType);
+                        _keyTypeInfo = Options.GetTypeInfoCached(KeyType);
                     }
                 }
                 else
@@ -735,7 +735,7 @@ internal void InitializePropertyCache()
                         ThrowHelper.ThrowInvalidOperationException_SerializerPropertyNameConflict(Type, property.Name);
                     }
 
-                    isOrderSpecified = property.Order != 0;
+                    isOrderSpecified |= property.Order != 0;
                 }
 
                 if (isOrderSpecified)
@@ -934,7 +934,7 @@ public JsonPropertyInfoList(JsonTypeInfo jsonTypeInfo)
             {
                 if (jsonTypeInfo.ExtensionDataProperty is not null)
                 {
-                    Add(jsonTypeInfo.ExtensionDataProperty);
+                    _list.Add(jsonTypeInfo.ExtensionDataProperty);
                 }
 
                 _jsonTypeInfo = jsonTypeInfo;

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/PolymorphicTypeResolver.cs

@@ -249,7 +249,7 @@ public DerivedJsonTypeInfo(Type type, object? typeDiscriminator)
             public Type DerivedType { get; }
             public object? TypeDiscriminator { get; }
             public JsonTypeInfo GetJsonTypeInfo(JsonSerializerOptions options)
-                => _jsonTypeInfo ??= options.GetJsonTypeInfoCached(DerivedType);
+                => _jsonTypeInfo ??= options.GetTypeInfoCached(DerivedType);
         }
     }
 }

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/ReadStack.cs

@@ -95,7 +95,7 @@ private void EnsurePushCapacity()
 
         public void Initialize(Type type, JsonSerializerOptions options, bool supportContinuation)
         {
-            JsonTypeInfo jsonTypeInfo = options.GetJsonTypeInfoForRootType(type);
+            JsonTypeInfo jsonTypeInfo = options.GetTypeInfoForRootType(type);
             Initialize(jsonTypeInfo, supportContinuation);
         }
 

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/WriteStack.cs

@@ -138,7 +138,7 @@ private void EnsurePushCapacity()
         /// </summary>
         public JsonConverter Initialize(Type type, JsonSerializerOptions options, bool supportContinuation, bool supportAsync)
         {
-            JsonTypeInfo jsonTypeInfo = options.GetJsonTypeInfoForRootType(type);
+            JsonTypeInfo jsonTypeInfo = options.GetTypeInfoForRootType(type);
             return Initialize(jsonTypeInfo, supportContinuation, supportAsync);
         }
 

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/WriteStackFrame.cs

@@ -126,7 +126,7 @@ public JsonConverter InitializePolymorphicReEntry(Type runtimeType, JsonSerializ
             // if the current element is the same type as the previous element.
             if (PolymorphicJsonTypeInfo?.PropertyType != runtimeType)
             {
-                JsonTypeInfo typeInfo = options.GetJsonTypeInfoCached(runtimeType);
+                JsonTypeInfo typeInfo = options.GetTypeInfoCached(runtimeType);
                 PolymorphicJsonTypeInfo = typeInfo.PropertyInfoForTypeInfo;
             }