Port away from deprecated create_* KCM loading

Task: https://phabricator.kde.org/T13808

src/CMakeLists.txt

@@ -94,7 +94,7 @@ ecm_qt_declare_logging_category(kcm_kdf_PART_SRCS
                                 CATEGORY_NAME kdf.kcm DESCRIPTION "kdf (kdf kcm)" EXPORT KDF)
 
 add_library(kcm_kdf ${kcm_kdf_PART_SRCS})
-
+kcoreaddons_desktop_to_json(kcm_kdf "../desktop/kcmdf.desktop" SERVICE_TYPES kcmodule.desktop)
 target_link_libraries(kcm_kdf
     kdfprivate
     Qt5::Core

src/kcmdf.cpp

@@ -28,9 +28,13 @@
 #include "kcmdf.h"
 
 #include <QVBoxLayout>
+#include <KPluginFactory>
+#include <kpluginfactory.h>
 
-KDiskFreeWidget::KDiskFreeWidget( QWidget *parent )
-        : KCModule( parent )
+K_PLUGIN_CLASS_WITH_JSON(KDiskFreeWidget, "kcmdf.json")
+
+KDiskFreeWidget::KDiskFreeWidget( QWidget *parent, const QVariantList &args )
+        : KCModule( parent, args )
 {
     setButtons(Help);
 
@@ -52,11 +56,4 @@ QString KDiskFreeWidget::quickHelp() const
                 " or to open it in the file manager.");
 }
 
-extern "C"
-{
-    Q_DECL_EXPORT KCModule* create_kdf( QWidget *parent, const char * /*name*/ )
-    {
-        return new KDiskFreeWidget( parent );
-    }
-}
-
+#include "kcmdf.moc"

src/kcmdf.h

@@ -34,7 +34,7 @@ class KDiskFreeWidget : public KCModule
     Q_OBJECT
 
     public:
-        explicit KDiskFreeWidget( QWidget *parent = nullptr  );
+        explicit KDiskFreeWidget( QWidget *parent = nullptr, const QVariantList &args = {});
         ~KDiskFreeWidget() override;
 
         QString quickHelp() const override;