[rygel] rygel: Fix compile error

[Jens Georg <jensgeorg src gnome org>]

commit ea83eb3cf44209c024249143f356f3f4982a56b7
Author: Jens Georg <mail jensge org>
Date:   Mon Aug 29 09:46:58 2016 +0200

    rygel: Fix compile error
    
    https://bugzilla.gnome.org/show_bug.cgi?id=770531

 src/rygel/rygel-cmdline-config.vala     |    6 +++---
 src/rygel/rygel-environment-config.vala |    6 +++---
 src/rygel/rygel-user-config.vala        |    6 +++---
 3 files changed, 9 insertions(+), 9 deletions(-)
---
diff --git a/src/rygel/rygel-cmdline-config.vala b/src/rygel/rygel-cmdline-config.vala
index 1764ea0..d16996f 100644
--- a/src/rygel/rygel-cmdline-config.vala
+++ b/src/rygel/rygel-cmdline-config.vala
@@ -277,15 +277,15 @@ public class Rygel.CmdlineConfig : GLib.Object, Configuration {
         return config_file;
     }
 
-    public string get_video_upload_folder () throws GLib.Error {
+    public string? get_video_upload_folder () throws GLib.Error {
         throw new ConfigurationError.NO_VALUE_SET (_("No value available"));
     }
 
-    public string get_music_upload_folder () throws GLib.Error {
+    public string? get_music_upload_folder () throws GLib.Error {
         throw new ConfigurationError.NO_VALUE_SET (_("No value available"));
     }
 
-    public string get_picture_upload_folder () throws GLib.Error {
+    public string? get_picture_upload_folder () throws GLib.Error {
         throw new ConfigurationError.NO_VALUE_SET (_("No value available"));
     }
 
diff --git a/src/rygel/rygel-environment-config.vala b/src/rygel/rygel-environment-config.vala
index fa0eb3b..c7800bb 100644
--- a/src/rygel/rygel-environment-config.vala
+++ b/src/rygel/rygel-environment-config.vala
@@ -96,15 +96,15 @@ internal class Rygel.EnvironmentConfig : GLib.Object, Configuration {
         return this.get_string_variable (MEDIA_ENGINE_ENV);
     }
 
-    public string get_video_upload_folder () throws GLib.Error {
+    public string? get_video_upload_folder () throws GLib.Error {
         throw new ConfigurationError.NO_VALUE_SET (_("No value available"));
     }
 
-    public string get_music_upload_folder () throws GLib.Error {
+    public string? get_music_upload_folder () throws GLib.Error {
         throw new ConfigurationError.NO_VALUE_SET (_("No value available"));
     }
 
-    public string get_picture_upload_folder () throws GLib.Error {
+    public string? get_picture_upload_folder () throws GLib.Error {
         throw new ConfigurationError.NO_VALUE_SET (_("No value available"));
     }
 
diff --git a/src/rygel/rygel-user-config.vala b/src/rygel/rygel-user-config.vala
index 5fd232c..2f8d53f 100644
--- a/src/rygel/rygel-user-config.vala
+++ b/src/rygel/rygel-user-config.vala
@@ -195,15 +195,15 @@ public class Rygel.UserConfig : GLib.Object, Configuration {
         return this.get_string (GENERAL_SECTION, MEDIA_ENGINE_KEY);
     }
 
-    public string get_video_upload_folder () throws GLib.Error {
+    public string? get_video_upload_folder () throws GLib.Error {
         return this.get_string (GENERAL_SECTION, VIDEO_UPLOAD_DIR_PATH_KEY);
     }
 
-    public string get_music_upload_folder () throws GLib.Error {
+    public string? get_music_upload_folder () throws GLib.Error {
         return this.get_string (GENERAL_SECTION, MUSIC_UPLOAD_DIR_PATH_KEY);
     }
 
-    public string get_picture_upload_folder () throws GLib.Error {
+    public string? get_picture_upload_folder () throws GLib.Error {
         return this.get_string (GENERAL_SECTION, PICTURE_UPLOAD_DIR_PATH_KEY);
     }