[connections] connection: Set default display_name as an empty string

[Felipe Borges <felipeborges src gnome org>]

commit ad00df8682d3c5a028c999f1e036966ce79f9f97
Author: Felipe Borges <felipeborges gnome org>
Date:   Fri Aug 6 09:08:42 2021 +0200

    connection: Set default display_name as an empty string
    
    Since we bind_property the Connection object properties to the
    equivalent GtkWidget in the preferences dialog, we need to make
    sure string properties are not NULL.

 src/connection.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/connection.vala b/src/connection.vala
index 7248cd4..ebd47cd 100644
--- a/src/connection.vala
+++ b/src/connection.vala
@@ -47,7 +47,7 @@ namespace Connections {
         public string host { get; protected set; }
         public abstract int port { get; protected set; }
         public string protocol { get; protected set; }
-        public string display_name { get; set; }
+        public string display_name { get; set; default = ""; }
 
         public abstract void send_keys (uint[] keys);