Ignore __type attr when trying to deserialize into KVP

Author: mythz

src/ServiceStack.Text/Common/DeserializeKeyValuePair.cs

@@ -74,7 +74,7 @@ public static object ParseKeyValuePair<TKey, TValue>(
                     keyValue = (TKey)parseKeyFn(keyElementValue);
                 else if (key.CompareIgnoreCase("value".AsSpan()))
                     valueValue = (TValue)parseValueFn(keyElementValue);
-                else
+                else if (!key.SequenceEqual(JsConfig.TypeAttr.AsSpan()))
                     throw new SerializationException("Incorrect KeyValuePair property: " + key.ToString());
 
                 Serializer.EatItemSeperatorOrMapEndChar(value, ref index);

tests/ServiceStack.Text.Tests/RuntimeSerializationTests.cs

@@ -332,5 +332,14 @@ private class MyProperty : IProperty
         {
             public string Value { get; set; }
         }
+
+        [Test]
+        public void Can_deserialize_object_into_string_dictionary()
+        {
+            var json = "{\"__type\":\"System.Collections.Generic.KeyValuePair`2[[System.String, System.Private.CoreLib],[System.String, System.Private.CoreLib]], System.Private.CoreLib\",\"Key\":\"A\",\"Value\":\"B\"}";
+            var dto = json.FromJson<KeyValuePair<string, string>>();
+            Assert.That(dto.Key, Is.EqualTo("A"));
+            Assert.That(dto.Value, Is.EqualTo("B"));
+        }
     }
 }