[gxml] Changing GLib.Value? property to GLib.Value

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit 5f95e527ed4056cc75397d2bfbdfa966b8097466
Author: Daniel Espinosa <esodan gmail com>
Date:   Wed Oct 18 15:52:41 2017 -0500

    Changing GLib.Value? property to GLib.Value
    
    This remove warnings, but now is necesary to check if
    GLib.Value is un set, to consider no value has been set,
    by using:
    
    GLib.Value.type ().is_a (Type.INVALID)

 gxml/DomEvents.vala     |    6 +++---
 gxml/GXmlDomEvents.vala |    4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)
---
diff --git a/gxml/DomEvents.vala b/gxml/DomEvents.vala
index 8aa7c40..bca322f 100644
--- a/gxml/DomEvents.vala
+++ b/gxml/DomEvents.vala
@@ -75,13 +75,13 @@ public class GXml.DomEventInit : GLib.Object {
 }
 
 public interface GXml.DomCustomEvent : GLib.Object, GXml.DomEvent {
-  public abstract GLib.Value? detail { get; }
+  public abstract GLib.Value detail { get; }
 
-  public abstract void init_custom_event (string type, bool bubbles, bool cancelable, GLib.Value? detail);
+  public abstract void init_custom_event (string type, bool bubbles, bool cancelable, GLib.Value detail);
 }
 
 public class GXml.DomCustomEventInit : GXml.DomEventInit {
-  public GLib.Value? detail { get; set; default = null; }
+  public GLib.Value detail { get; set; }
 }
 
 
diff --git a/gxml/GXmlDomEvents.vala b/gxml/GXmlDomEvents.vala
index f7d0b22..740ce18 100644
--- a/gxml/GXmlDomEvents.vala
+++ b/gxml/GXmlDomEvents.vala
@@ -69,8 +69,8 @@ public class GXml.GDomEvent : Object, GXml.DomEvent {
  * Custom event handler, powered by libxml2 library.
  */
 public class GXml.GDomCustomEvent : GXml.GDomEvent {
-       protected GLib.Value? _detail;
-       public GLib.Value? detail { get { return _detail; } }
+       protected GLib.Value _detail;
+       public GLib.Value detail { get { return _detail; } }
 
        public void init_custom_event (string type, bool bubbles, bool cancelable, GLib.Value? detail)
        {