message: objc: In Aead mark AdditionalData as nullable, this is needed in Swift when a parameter is optional.
  GitOrigin-RevId:
diff: @@ -34,11 +34,11 @@ NS_ASSUME_NONNULL_BEGIN
  * additional data, but does not guarantee its secrecy.
  *
  * @param plaintext The data to encrypt.
  - * @param additionalData Additional authenticated data.
  + * @param additionalData Additional authenticated data. (optional)
  * @return The encrypted data on success; nil in case of error.
  */
  - (nullable NSData *)encrypt:(NSData *)plaintext
  - withAdditionalData:(NSData *)additionalData
  + withAdditionalData:(nullable NSData *)additionalData
  error:(NSError **)error;
  /**
  @@ -47,11 +47,11 @@ NS_ASSUME_NONNULL_BEGIN
  * data, but there are no guarantees with regards to secrecy of that data.
  *
  * @param ciphertext The data to decrypt.
  - * @param additionalData Additional authenticated data.
  + * @param additionalData Additional authenticated data. (optional)
  * @return The decrypted data on success; nil in case of error.
  */
  - (nullable NSData *)decrypt:(NSData *)ciphertext
  - withAdditionalData:(NSData *)additionalData
  + withAdditionalData:(nullable NSData *)additionalData
  error:(NSError **)error;
  @end
  