[folks] Guarantee all NoteFieldDetails members are non-null.

[Travis Reitter <treitter src gnome org>]

commit 25a17b0ca731ce8f9140e2c09ff60003cc5f1b9e
Author: Travis Reitter <travis reitter collabora co uk>
Date:   Fri Oct 21 10:11:55 2011 -0700

    Guarantee all NoteFieldDetails members are non-null.
    
    Helps: bgo#662433 - AbstractFieldDetails.equal() is ambiguous about
    checking parameters.

 folks/note-details.vala |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)
---
diff --git a/folks/note-details.vala b/folks/note-details.vala
index 4b8f14e..80c27d3 100644
--- a/folks/note-details.vala
+++ b/folks/note-details.vala
@@ -33,10 +33,16 @@ using GLib;
  */
 public class Folks.NoteFieldDetails : AbstractFieldDetails<string>
 {
+  /* FIXME: deprecate this */
+  private string _uid;
   /**
    * The UID of the note (if any).
    */
-  public string uid { get; set; }
+  public string uid
+    {
+      get { return _uid; }
+      set { _uid = (value != null ? value : ""); }
+    }
 
   /**
    * Create a new NoteFieldDetails.