operation.setOperator(Operator.ADD);
CampaignAdExtensionOperation[] operations = new CampaignAdExtensionOperation[] {operation};
// Add campaign ad extension.
CampaignAdExtensionReturnValue result = campaignAdExtensionService.mutate(operations);
// Display campaign ad extensions.
if (result != null && result.getValue() != null) {
for (CampaignAdExtension campaignAdExtensionResult : result.getValue()) {
System.out.println("Campaign ad extension with campaign id \""