[geary/mjog/invert-folder-class-hierarchy: 358/362] Geary.App.ConversationMonitor: Fix list of required fields

[Michael Gratton <mjog src gnome org>]

commit 8e385f7548fde51a5ee9f8581243d66a77c082d5
Author: Michael Gratton <mike vee net>
Date:   Sun Feb 21 17:02:59 2021 +1100

    Geary.App.ConversationMonitor: Fix list of required fields
    
    Add properties since that's needed to be able to order by received date.

 src/engine/app/app-conversation-monitor.vala | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
---
diff --git a/src/engine/app/app-conversation-monitor.vala b/src/engine/app/app-conversation-monitor.vala
index 8c1751ecc..c773ac399 100644
--- a/src/engine/app/app-conversation-monitor.vala
+++ b/src/engine/app/app-conversation-monitor.vala
@@ -47,9 +47,12 @@ public class Geary.App.ConversationMonitor : BaseObject, Logging.Source {
      * parameter passed to the constructor.
      */
     public const Geary.Email.Field REQUIRED_FIELDS = (
-        Geary.Email.Field.REFERENCES |
-        Geary.Email.Field.FLAGS |
-        Geary.Email.Field.DATE
+        // Required for linking email into conversations
+        REFERENCES |
+        // Required for checking for deleted flags
+        FLAGS |
+        // Required for checking ordering conversations
+        DATE | PROPERTIES
     );
 
     /** The GLib logging domain used by this class. */