Honor custom number handling only when property/type is a number/collection of numbers

src/libraries/System.Text.Json/src/Resources/Strings.resx

@@ -540,7 +540,7 @@
     <value>'JsonNumberHandlingAttribute' cannot be placed on a property, field, or type that is handled by a custom converter. See usage(s) of converter '{0}' on type '{1}'.</value>
   </data>
   <data name="NumberHandlingOnPropertyTypeMustBeNumberOrCollection" xml:space="preserve">
-    <value>When 'JsonNumberHandlingAttribute' is placed on a property or field, the property or field must be a number or a collection. See member '{0}' on type '{1}'.</value>
+    <value>When 'JsonNumberHandlingAttribute' is placed on a property or field, the property or field must be a number or a collection of numbers. See member '{0}' on type '{1}'.</value>
   </data>
   <data name="ConverterCanConvertNullableRedundant" xml:space="preserve">
     <value>The converter '{0}' handles type '{1}' but is being asked to convert type '{2}'. Either create a separate converter for type '{2}' or change the converter's 'CanConvert' method to only return 'true' for a single type.</value>

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Value/ObjectConverter.cs

@@ -5,6 +5,11 @@ namespace System.Text.Json.Serialization.Converters
 {
     internal sealed class ObjectConverter : JsonConverter<object>
     {
+        public ObjectConverter()
+        {
+            IsInternalConverterForNumberType = true;
+        }
+
         public override object Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
         {
             using (JsonDocument document = JsonDocument.ParseValue(ref reader))
@@ -37,5 +42,13 @@ private JsonConverter GetRuntimeConverter(Type runtimeType, JsonSerializerOption
 
             return runtimeConverter;
         }
+
+        internal override object ReadNumberWithCustomHandling(ref Utf8JsonReader reader, JsonNumberHandling handling)
+        {
+            using (JsonDocument document = JsonDocument.ParseValue(ref reader))
+            {
+                return document.RootElement.Clone();
+            }
+        }
     }
 }

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

@@ -163,7 +163,7 @@ internal bool TryRead(ref Utf8JsonReader reader, Type typeToConvert, JsonSeriali
                 // For performance, only perform validation on internal converters on debug builds.
                 if (IsInternalConverter)
                 {
-                    if (IsInternalConverterForNumberType && state.Current.NumberHandling != null)
+                    if (state.Current.NumberHandling != null)
                     {
                         value = ReadNumberWithCustomHandling(ref reader, state.Current.NumberHandling.Value);
                     }
@@ -179,7 +179,7 @@ internal bool TryRead(ref Utf8JsonReader reader, Type typeToConvert, JsonSeriali
                     int originalPropertyDepth = reader.CurrentDepth;
                     long originalPropertyBytesConsumed = reader.BytesConsumed;
 
-                    if (IsInternalConverterForNumberType && state.Current.NumberHandling != null)
+                    if (state.Current.NumberHandling != null)
                     {
                         value = ReadNumberWithCustomHandling(ref reader, state.Current.NumberHandling.Value);
                     }
@@ -356,7 +356,7 @@ internal bool TryWrite(Utf8JsonWriter writer, in T value, JsonSerializerOptions
 
                 int originalPropertyDepth = writer.CurrentDepth;
 
-                if (IsInternalConverterForNumberType && state.Current.NumberHandling != null)
+                if (state.Current.NumberHandling != null && IsInternalConverterForNumberType)
                 {
                     WriteNumberWithCustomHandling(writer, value, state.Current.NumberHandling.Value);
                 }

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

@@ -184,52 +184,89 @@ private void DetermineIgnoreCondition(JsonIgnoreCondition? ignoreCondition, bool
 
         private void DetermineNumberHandling(JsonNumberHandling? parentTypeNumberHandling)
         {
+            bool numberHandlingIsApplicable = ConverterBase.IsInternalConverterForNumberType || TypeIsCollectionOfNumbersWithInternalConverter();
+
             if (IsForClassInfo)
             {
                 if (parentTypeNumberHandling != null && !ConverterBase.IsInternalConverter)
                 {
                     ThrowHelper.ThrowInvalidOperationException_NumberHandlingOnPropertyInvalid(this);
                 }
 
-                // Priority 1: Get handling from the type (parent type in this case is the type itself).
-                NumberHandling = parentTypeNumberHandling;
-
-                // Priority 2: Get handling from JsonSerializerOptions instance.
-                if (!NumberHandling.HasValue && Options.NumberHandling != JsonNumberHandling.Strict)
+                if (numberHandlingIsApplicable)
                 {
-                    NumberHandling = Options.NumberHandling;
+                    // This logic is to honor JsonNumberHandlingAttribute placed on
+                    // custom collections e.g. public class MyNumberList : List<int>.
+
+                    // Priority 1: Get handling from the type (parent type in this case is the type itself).
+                    NumberHandling = parentTypeNumberHandling;
+
+                    // Priority 2: Get handling from JsonSerializerOptions instance.
+                    if (!NumberHandling.HasValue && Options.NumberHandling != JsonNumberHandling.Strict)
+                    {
+                        NumberHandling = Options.NumberHandling;
+                    }
                 }
             }
             else
             {
-                JsonNumberHandling? handling = null;
+                Debug.Assert(MemberInfo != null);
+
+                JsonNumberHandlingAttribute? attribute = GetAttribute<JsonNumberHandlingAttribute>(MemberInfo);
+                if (attribute != null && !numberHandlingIsApplicable)
+                {
+                    ThrowHelper.ThrowInvalidOperationException_NumberHandlingOnPropertyInvalid(this);
+                }
 
-                // Priority 1: Get handling from attribute on property or field.
-                if (MemberInfo != null)
+                if (numberHandlingIsApplicable)
                 {
-                    JsonNumberHandlingAttribute? attribute = GetAttribute<JsonNumberHandlingAttribute>(MemberInfo);
+                    // Priority 1: Get handling from attribute on property or field.
+                    JsonNumberHandling? handling = attribute?.Handling;
+
+                    // Priority 2: Get handling from attribute on parent class type.
+                    handling ??= parentTypeNumberHandling;
 
-                    if (attribute != null &&
-                        !ConverterBase.IsInternalConverterForNumberType &&
-                        ((ClassType.Enumerable | ClassType.Dictionary) & ClassType) == 0)
+                    // Priority 3: Get handling from JsonSerializerOptions instance.
+                    if (!handling.HasValue && Options.NumberHandling != JsonNumberHandling.Strict)
                     {
-                        ThrowHelper.ThrowInvalidOperationException_NumberHandlingOnPropertyInvalid(this);
+                        handling = Options.NumberHandling;
                     }
 
-                    handling = attribute?.Handling;
+                    NumberHandling = handling;
                 }
+            }
+        }
 
-                // Priority 2: Get handling from attribute on parent class type.
-                handling ??= parentTypeNumberHandling;
-
-                // Priority 3: Get handling from JsonSerializerOptions instance.
-                if (!handling.HasValue && Options.NumberHandling != JsonNumberHandling.Strict)
-                {
-                    handling = Options.NumberHandling;
-                }
+        private bool TypeIsCollectionOfNumbersWithInternalConverter()
+        {
+            if (!ConverterBase.IsInternalConverter ||
+                ((ClassType.Enumerable | ClassType.Dictionary) & ClassType) == 0)
+            {
+                return false;
+            }
 
-                NumberHandling = handling;
+            Type? elementType = ConverterBase.ElementType;
+            Debug.Assert(elementType != null);
+
+            elementType = Nullable.GetUnderlyingType(elementType) ?? elementType;
+
+            if (elementType == typeof(byte) ||
+                elementType == typeof(decimal) ||
+                elementType == typeof(double) ||
+                elementType == typeof(short) ||
+                elementType == typeof(int) ||
+                elementType == typeof(long) ||
+                elementType == typeof(sbyte) ||
+                elementType == typeof(float) ||
+                elementType == typeof(ushort) ||
+                elementType == typeof(uint) ||
+                elementType == typeof(ulong) ||
+                elementType == JsonClassInfo.ObjectType)
+            {
+                return true;
             }
+
+            return false;
         }
 
         public static TAttribute? GetAttribute<TAttribute>(MemberInfo memberInfo) where TAttribute : Attribute