Merge pull request #102 from Kentico/fix/reference-null-values

Fix serializing null value in reference custom data fields

Author: fialafilip

src/Kentico.Xperience.UMT/Services/ContentItemReferencePopulator.cs

@@ -1,12 +1,12 @@
-using CMS.ContentEngine.Internal;
+using System.Text.Json;
+
 using CMS.ContentEngine;
+using CMS.ContentEngine.Internal;
 using CMS.DataEngine;
 using CMS.FormEngine;
 
 using Kentico.Xperience.UMT.Utils;
 
-using System.Text.Json;
-
 namespace Kentico.Xperience.UMT.Services
 {
     internal class ContentItemReferencePopulator
@@ -24,7 +24,7 @@ internal static void Preprocess(
                                                 .Select(field => (FieldName: field.Name, Value: customData[field.Name]))
                                                 .Where(x => x.Value is not string))
             {
-                customData[fieldName] = JsonSerializer.Serialize(value);
+                customData[fieldName] = value is not null ? JsonSerializer.Serialize(value, new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase }) : null;
             }
         }
 
@@ -77,7 +77,7 @@ ContentItemCommonDataInfo commonDataInfo
                 {
                     if (contentItemReferenceFieldValue is string serializedValue)
                     {
-                        var value = JsonSerializer.Deserialize<IEnumerable<ContentItemReference>>(serializedValue);
+                        var value = JsonSerializer.Deserialize<IEnumerable<ContentItemReference>?>(serializedValue, new JsonSerializerOptions { PropertyNameCaseInsensitive = true });
                         if (value is not null)
                         {
                             foreach (var targetItemGuid in value.Select(x => x.Identifier))