(#384) Changed DateTimeConverter on client and server side to handle 'default' DateTime correctly.

Author: StefanCuypers

src/CommunityToolkit.Datasync.Client/Serialization/DateTimeConverter.cs

@@ -26,6 +26,13 @@ public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, Jso
         }
         else
         {
+            // Check if datetime was 'default'. If so do not adjust to local time.
+            DateTime utc = DateTime.Parse(token, CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal | DateTimeStyles.AssumeUniversal);
+            if (utc == default)
+            {
+                return utc;
+            }
+
             return DateTime.Parse(token);
         }
     }

src/CommunityToolkit.Datasync.Server.Abstractions/Json/DateTimeConverter.cs

@@ -18,7 +18,24 @@ public class DateTimeConverter : JsonConverter<DateTime>
 
     /// <inheritdoc />
     public override DateTime Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
-        => DateTime.Parse(reader.GetString() ?? string.Empty);
+    {
+        string? token = reader.GetString();
+        if (string.IsNullOrEmpty(token))
+        {
+            return DateTime.MinValue;
+        }
+        else
+        {
+            // Check if datetime was 'default'. If so do not adjust to local time.
+            DateTime utc = DateTime.Parse(token, CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal | DateTimeStyles.AssumeUniversal);
+            if (utc == default)
+            {
+                return utc;
+            }
+
+            return DateTime.Parse(token);
+        }
+    }
 
     /// <inheritdoc />
     public override void Write(Utf8JsonWriter writer, DateTime value, JsonSerializerOptions options)