Add nullability annotations to util classes.

Mobile Buy SDK/Mobile Buy SDK/Utils/BUYApplePayAdditions.h

@@ -30,6 +30,7 @@
 #import <Buy/BUYCheckout.h>
 #import <Buy/BUYShippingRate.h>
 #import <Buy/BUYAddress.h>
+NS_ASSUME_NONNULL_BEGIN
 
 @interface BUYCheckout (ApplePay)
 
@@ -37,7 +38,7 @@
  *  Returns an array of summary items for all Apple Pay requests.  Will use 'PAY TOTAL' as the summary label.  Apple recommends
  *  including the business name in the summary label, so it is recommended to use `buy_summaryItemsWithShopName` instead.
  */
-- (nonnull NSArray<PKPaymentSummaryItem *> *)buy_summaryItems;
+- (NSArray<PKPaymentSummaryItem *> *)buy_summaryItems;
 
 /**
  *  Returns an array of summary items for all Apple Pay requests using the shop name in the "PAY" section
@@ -46,7 +47,7 @@
  *
  *  @return An array of PKPaymentSummaryItems
  */
-- (nonnull NSArray<PKPaymentSummaryItem *> *)buy_summaryItemsWithShopName:(nullable NSString *)shopName;
+- (NSArray<PKPaymentSummaryItem *> *)buy_summaryItemsWithShopName:(nullable NSString *)shopName;
 
 @end
 
@@ -59,7 +60,7 @@
 *
 *  @return An array of PKShippingMethods
 */
-+ (nonnull NSArray<PKShippingMethod *> *)buy_convertShippingRatesToShippingMethods:(nonnull NSArray<BUYShippingRate *> *)rates;
++ (NSArray<PKShippingMethod *> *)buy_convertShippingRatesToShippingMethods:(NSArray<BUYShippingRate *> *)rates;
 
 @end
 
@@ -72,3 +73,5 @@
 - (void)updateWithContact:(nullable PKContact*)contact NS_AVAILABLE_IOS(9_0);
 
 @end
+
+NS_ASSUME_NONNULL_END

Mobile Buy SDK/Mobile Buy SDK/Utils/BUYError+BUYAdditions.h

@@ -25,12 +25,20 @@
 //
 
 #import <Buy/BUYError.h>
+NS_ASSUME_NONNULL_BEGIN
 
 @interface BUYError (Checkout)
-+ (NSArray<BUYError *> *)errorsFromCheckoutJSON:(NSDictionary *)json;
+
 @property (readonly) NSString *quantityRemainingMessage;
+
++ (nullable NSArray<BUYError *> *)errorsFromCheckoutJSON:(NSDictionary *)json;
+
 @end
 
 @interface BUYError (Customer)
+
 + (NSArray<BUYError *> *)errorsFromSignUpJSON:(NSDictionary *)json;
+
 @end
+
+NS_ASSUME_NONNULL_END

Mobile Buy SDK/Mobile Buy SDK/Utils/BUYModelManager+ApplePay.h

@@ -24,8 +24,9 @@
 //  THE SOFTWARE.
 //
 
-#import <Buy/BUYModelManager.h>
 @import PassKit;
+#import "BUYModelManager.h"
+NS_ASSUME_NONNULL_BEGIN
 
 @class BUYAddress;
 
@@ -50,3 +51,5 @@
 - (BUYAddress *)buyAddressWithContact:(PKContact *)contact NS_AVAILABLE_IOS(9_0);
 
 @end
+
+NS_ASSUME_NONNULL_END