Change acccess modifiers

Signed-off-by: alperozturk <alper_ozturk@proton.me>

app/src/main/java/com/owncloud/android/ui/activity/FolderPickerActivity.kt

@@ -76,9 +76,9 @@ open class FolderPickerActivity :
         private set
 
     private var mCancelBtn: MaterialButton? = null
-    var mCopyBtn: MaterialButton? = null
-    var mChooseBtn: MaterialButton? = null
-    var mMoveBtn: MaterialButton? = null
+    private var mCopyBtn: MaterialButton? = null
+    private var mChooseBtn: MaterialButton? = null
+    private var mMoveBtn: MaterialButton? = null
 
     private var caption: String? = null