@Override
  public Mac getPrimitive(ByteString serializedKey) throws GeneralSecurityException {
    try {
      HmacKey keyProto = HmacKey.parseFrom(serializedKey, ExtensionRegistryLite.getEmptyRegistry());
      return getPrimitive(keyProto);
    } catch (InvalidProtocolBufferException e) {
      throw new GeneralSecurityException("expected serialized HmacKey proto", e);
    }
  }
@param serializedKey serialized {@code HmacKey} proto
java_src/src/main/java/com/google/crypto/tink/mac/internal/LegacyHmacTestKeyManager.java