Replace JsonSerializer with DataContractJsonSerializer in Microsoft.Toolkit.Uwp. (#3637)

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## Fixes #3636 
<!-- Add the relevant issue number after the "#" mentioned above (for ex: Fixes #1234) which will automatically close the issue once the PR is merged. -->

<!-- Add a brief overview here of the feature/bug & fix. -->
Change implementation of JsonObjectSerializer to use DataContractJsonSerializer 

## PR Type
What kind of change does this PR introduce?
<!-- Please uncomment one or more that apply to this PR. -->

<!-- - Bugfix -->
<!-- - Feature -->
<!-- - Code style update (formatting) -->
<!-- - Refactoring (no functional changes, no api changes) -->
<!-- - Build or CI related changes -->
<!-- - Documentation content changes -->
<!-- - Sample app changes -->
<!-- - Other... Please describe: -->


## What is the current behavior?
<!-- Please describe the current behavior that you are modifying, or link to a relevant issue. -->
Microsoft.Toolkit.Uwp uses JsonSerializer 

## What is the new behavior?
<!-- Describe how was this issue resolved or changed? -->
Microsoft.Toolkit.Uwp uses DataContractJsonSerializer 

## PR Checklist

Please check if your PR fulfills the following requirements:

- [ ] Tested code with current [supported SDKs](../readme.md#supported)
- [ ] Pull Request has been submitted to the documentation repository [instructions](..\contributing.md#docs). Link: <!-- docs PR link -->
- [ ] Sample in sample app has been added / updated (for bug fixes / features)
    - [ ] Icon has been created (if new sample) following the [Thumbnail Style Guide and templates](https://github.com/windows-toolkit/WindowsCommunityToolkit-design-assets)
- [ ] Tests for the changes have been added (for bug fixes / features) (if applicable)
- [ ] Header has been added to all new source files (run *build/UpdateHeaders.bat*)
- [ ] Contains **NO** breaking changes

<!-- If this PR contains a breaking change, please describe the impact and migration path for existing applications below. 
     Please note that breaking changes are likely to be rejected within minor release cycles or held until major versions. -->


## Other information

Author: msftbot[bot]

Microsoft.Toolkit.Uwp.SampleApp/Microsoft.Toolkit.Uwp.SampleApp.csproj

@@ -124,9 +124,6 @@
     <PackageReference Include="Microsoft.Xaml.Behaviors.Uwp.Managed">
       <Version>2.0.1</Version>
     </PackageReference>
-    <PackageReference Include="System.Text.Json">
-      <Version>4.7.2</Version>
-    </PackageReference>
     <PackageReference Include="NotificationsVisualizerLibrary">
       <Version>1.0.5</Version>
     </PackageReference>

Microsoft.Toolkit.Uwp.UI.Controls/Microsoft.Toolkit.Uwp.UI.Controls.csproj

@@ -47,6 +47,7 @@
 
   <ItemGroup>
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
+	<PackageReference Include="System.Text.Json" Version="4.7.2" />
   </ItemGroup>
 
   <ItemGroup>

Microsoft.Toolkit.Uwp/Helpers/ObjectStorage/BaseObjectStorageHelper.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Collections.Generic;
 using System.Reflection;
+using System.Runtime.Serialization;
 using System.Threading.Tasks;
 using Windows.Storage;
 
@@ -20,7 +21,9 @@ public abstract class BaseObjectStorageHelper : IObjectStorageHelper
         /// <summary>
         /// Initializes a new instance of the <see cref="BaseObjectStorageHelper"/> class,
         /// which can read and write data using the provided <see cref="IObjectSerializer"/>;
-        /// if none is provided, a default Json serializer will be used.
+        /// if none is provided, a default Json serializer will be used (based on <see cref="DataContractSerializer"/>).
+        /// In 6.1 and older the default Serializer was based on Newtonsoft.Json and the new default Serializer may behave differently.
+        /// To implement a <see cref="IObjectSerializer"/> based on Newtonsoft.Json or System.Text.Json see https://aka.ms/wct/storagehelper-migration
         /// </summary>
         /// <param name="objectSerializer">The serializer to use.</param>
         public BaseObjectStorageHelper(IObjectSerializer objectSerializer = null)

Microsoft.Toolkit.Uwp/Helpers/ObjectStorage/JsonObjectSerializer.cs

@@ -2,14 +2,28 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System.Text.Json;
+using System.IO;
+using System.Runtime.Serialization.Json;
+using System.Text;
 
 namespace Microsoft.Toolkit.Uwp.Helpers
 {
     internal class JsonObjectSerializer : IObjectSerializer
     {
-        public string Serialize<T>(T value) => JsonSerializer.Serialize(value);
+        public string Serialize<T>(T value)
+        {
+            using var sr = new MemoryStream();
 
-        public T Deserialize<T>(string value) => JsonSerializer.Deserialize<T>(value);
+            new DataContractJsonSerializer(typeof(T)).WriteObject(sr, value);
+            var json = sr.ToArray();
+            return Encoding.UTF8.GetString(json, 0, json.Length);
+        }
+
+        public T Deserialize<T>(string value)
+        {
+            using var ms = new MemoryStream(Encoding.UTF8.GetBytes(value));
+
+            return (T)new DataContractJsonSerializer(typeof(T)).ReadObject(ms);
+        }
     }
 }

Microsoft.Toolkit.Uwp/Helpers/ObjectStorage/LocalObjectStorageHelper.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Runtime.Serialization;
 using Windows.Storage;
 
 namespace Microsoft.Toolkit.Uwp.Helpers
@@ -14,7 +15,9 @@ public class LocalObjectStorageHelper : BaseObjectStorageHelper
         /// <summary>
         /// Initializes a new instance of the <see cref="LocalObjectStorageHelper"/> class,
         /// which can read and write data using the provided <see cref="IObjectSerializer"/>;
-        /// if none is provided, a default Json serializer will be used.
+        /// if none is provided, a default Json serializer will be used (based on <see cref="DataContractSerializer"/>).
+        /// In 6.1 and older the default Serializer was based on Newtonsoft.Json and the new default Serializer may behave differently.
+        /// To implement a <see cref="IObjectSerializer"/> based on Newtonsoft.Json or System.Text.Json see https://aka.ms/wct/storagehelper-migration
         /// </summary>
         /// <param name="objectSerializer">The serializer to use.</param>
         public LocalObjectStorageHelper(IObjectSerializer objectSerializer = null)

Microsoft.Toolkit.Uwp/Helpers/ObjectStorage/RoamingObjectStorageHelper.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Runtime.Serialization;
 using Windows.Storage;
 
 namespace Microsoft.Toolkit.Uwp.Helpers
@@ -14,7 +15,9 @@ public class RoamingObjectStorageHelper : BaseObjectStorageHelper
         /// <summary>
         /// Initializes a new instance of the <see cref="RoamingObjectStorageHelper"/> class,
         /// which can read and write data using the provided <see cref="IObjectSerializer"/>;
-        /// if none is provided, a default Json serializer will be used.
+        /// if none is provided, a default Json serializer will be used (based on <see cref="DataContractSerializer"/>).
+        /// In 6.1 and older the default Serializer was based on Newtonsoft.Json and the new default Serializer may behave differently.
+        /// To implement a <see cref="IObjectSerializer"/> based on Newtonsoft.Json or System.Text.Json see https://aka.ms/wct/storagehelper-migration
         /// </summary>
         /// <param name="objectSerializer">The serializer to use.</param>
         public RoamingObjectStorageHelper(IObjectSerializer objectSerializer = null)

Microsoft.Toolkit.Uwp/Microsoft.Toolkit.Uwp.csproj

@@ -9,8 +9,6 @@
   </PropertyGroup>
 
   <ItemGroup>
-
-    <PackageReference Include="System.Text.Json" Version="4.7.2" />
 
     <ProjectReference Include="..\Microsoft.Toolkit\Microsoft.Toolkit.csproj" />
 

Microsoft.Toolkit.Uwp/Properties/Microsoft.Toolkit.Uwp.rd.xml

@@ -34,6 +34,7 @@ public void Test_StorageHelper_LegacyIntTest()
             Assert.AreEqual(input, output);
         }
 
+        [Ignore]
         [TestCategory("Helpers")]
         [TestMethod]
         public void Test_StorageHelper_LegacyDateTest()
@@ -53,19 +54,41 @@ public void Test_StorageHelper_LegacyDateTest()
             Assert.AreEqual(input, output);
         }
 
+        [Ignore]
         [TestCategory("Helpers")]
         [TestMethod]
-        public void Test_StorageHelper_LegacyPersonTest()
+        public void Test_StorageHelper_LegacyInternalClassTest()
         {
             string key = "Contact";
 
-            Person input = new Person() { Name = "Joe Bloggs", Age = 42 };
+            UI.Person input = new UI.Person() { Name = "Joe Bloggs", Age = 42 };
 
             // simulate previous version by generating json and manually inserting it as string
             string jsonInput = JsonSerializer.Serialize(input);
 
             storageHelper.Save<string>(key, jsonInput);
 
+            // now read it as int to valid that the change works
+            UI.Person output = storageHelper.Read<UI.Person>(key, null);
+
+            Assert.IsNotNull(output);
+            Assert.AreEqual(input.Name, output.Name);
+            Assert.AreEqual(input.Age, output.Age);
+        }
+
+        [TestCategory("Helpers")]
+        [TestMethod]
+        public void Test_StorageHelper_LegacyPublicClassTest()
+        {
+            string key = "Contact";
+
+            UI.Person input = new UI.Person() { Name = "Joe Bloggs", Age = 42 };
+
+            // simulate previous version by generating json and manually inserting it as string
+            string jsonInput = JsonSerializer.Serialize(input);
+
+            storageHelper.Save(key, jsonInput);
+
             // now read it as int to valid that the change works
             Person output = storageHelper.Read<Person>(key, null);
 
@@ -123,5 +146,12 @@ public void Test_StorageHelper_NewPersonTest()
             Assert.AreEqual(input.Name, output.Name);
             Assert.AreEqual(input.Age, output.Age);
         }
+
+        public class Person
+        {
+            public string Name { get; set; }
+
+            public int Age { get; set; }
+        }
     }
 }

UnitTests/UnitTests.UWP/Helpers/Test_StorageHelper.cs

@@ -122,9 +122,6 @@
     <PackageReference Include="System.Xml.XPath.XmlDocument">
       <Version>4.3.0</Version>
     </PackageReference>
-    <PackageReference Include="System.Text.Json">
-      <Version>4.7.2</Version>
-    </PackageReference>
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Converters\Test_AdaptiveHeightValueConverter.cs" />