PEC success emails not saved or included in response

src/main/java/net/gepafin/tendermanagement/entities/EmailSendResponseConverter.java

@@ -18,6 +18,9 @@ public class EmailSendResponseConverter implements AttributeConverter<List<Email
     @Override
     public String convertToDatabaseColumn(List<EmailSendResponse> attribute) {
         try {
+            if (attribute == null) {
+                attribute = List.of();
+            }
             return objectMapper.writeValueAsString(attribute);
         } catch (JsonProcessingException e) {
             throw new IllegalArgumentException("Error converting list to JSON", e);