public static Campaign createCampaign(
     String name, LinkedResource[] linked_ads, LinkedResource linked_contact) {
   Campaign campaign = new Campaign();
   campaign.name = name;
   campaign.linked_ads = linked_ads;
   campaign.linked_contact = linked_contact;
   return campaign;
 }
 public static Campaign createCampaign(String name, LinkedResource[] linked_ads) {
   return Campaign.createCampaign(name, linked_ads, null);
 }