/**
  * @see com.jdroid.android.billing.BillingManager#purchaseStateChanged(java.lang.String,
  *     java.lang.String)
  */
 @Override
 public void purchaseStateChanged(String signedData, String signature) {
   List<PurchaseOrder> orders = Security.verifyPurchase(signedData, signature);
   if ((orders != null) && !orders.isEmpty()) {
     BillingResponseHandler.notifyPurchaseStateChanged(orders);
   }
 }