Fix wrong type name serialization due to the plus sign '+' is escaped.

serialization/EasyCaching.Serialization.SystemTextJson/DefaultJsonSerializer.cs

@@ -3,6 +3,7 @@
 using System;
 using System.IO;
 using System.Text;
+using System.Text.Encodings.Web;
 using System.Text.Json;
 
 namespace EasyCaching.Serialization.SystemTextJson
@@ -17,6 +18,10 @@ public class DefaultJsonSerializer : IEasyCachingSerializer
         /// </summary>
         private readonly JsonSerializerOptions jsonSerializerOption;
         /// <summary>
+        /// The option for Utf8JsonWriter.
+        /// </summary>
+        private readonly JsonWriterOptions _jsonWriterOption;
+        /// <summary>
         /// The name.
         /// </summary>
         private readonly string _name;
@@ -35,6 +40,10 @@ public DefaultJsonSerializer(string name, JsonSerializerOptions serializerSettin
         {
             _name = name;
             jsonSerializerOption = serializerSettings;
+
+            // NOTE: We must use UnsafeRelaxedJsonEscaping instead of the encoder from JsonSerializerOptions,
+            // because we must ensure that the plus sign '+', which is the part of a nested class, is not escaped when writing type name.
+            _jsonWriterOption = new JsonWriterOptions { Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping };
         }
 
         /// <summary>
@@ -64,7 +73,7 @@ public object Deserialize(byte[] bytes, Type type)
         /// <param name="value">Value.</param>
         public object DeserializeObject(ArraySegment<byte> value)
         {
-            var jr = new Utf8JsonReader(value);
+            var jr = new Utf8JsonReader(value); // the JsonReaderOptions will be used here, which works well.
             jr.Read();
             if (jr.TokenType == JsonTokenType.StartArray)
             {
@@ -101,7 +110,7 @@ public ArraySegment<byte> SerializeObject(object obj)
             var typeName = TypeHelper.BuildTypeName(obj.GetType());
 
             using (var ms = new MemoryStream())
-            using (var jw = new Utf8JsonWriter(ms))
+            using (var jw = new Utf8JsonWriter(ms, _jsonWriterOption)) 
             {
                 jw.WriteStartArray();
                 jw.WriteStringValue(typeName);

test/EasyCaching.UnitTests/SerializerTests/SystemTestJsonSerializerTest.cs

@@ -59,7 +59,7 @@ public void NullValueHandling_Test_Should_Succeed()
             var serializer = new DefaultJsonSerializer("json", new JsonSerializerOptions
             {
                 DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull
-            }) ;
+            });
 
             Employee joe = new Employee { Name = "Joe User" };
 
@@ -68,5 +68,19 @@ public void NullValueHandling_Test_Should_Succeed()
 
             Assert.Null(joe.Manager);
         }
+
+        [Fact]
+        public void SerializeObject_NestedClass_Test_Should_Succeed()
+        {
+            var serializer = new DefaultJsonSerializer("json", new JsonSerializerOptions());
+
+            Employee joe = new Employee { Name = "Joe User" };
+
+            var joe_byte = serializer.SerializeObject(joe);
+            var joe_obj = serializer.DeserializeObject(joe_byte);
+
+            Assert.IsType<Employee>(joe_obj);
+            Assert.Equal(joe.Name, ((Employee)joe_obj).Name);
+        }
     }
 }