function toArray()
{
$notification = ['title' => $this->title, 'body' => $this->body, 'icon' => $this->icon, 'sound' => $this->sound, 'badge' => $this->badge, 'tag' => $this->tag, 'color' => $this->color, 'click_action' => $this->clickAction, 'body_loc_key' => $this->bodyLocationKey, 'body_loc_args' => $this->bodyLocationArgs, 'title_loc_key' => $this->titleLocationKey, 'title_loc_args' => $this->titleLocationArgs];
// remove null values
$notification = array_filter($notification);
return $notification;
}