private static ProtoKeySerialization serializeKey(AesEaxKey key, @Nullable SecretKeyAccess access)
      throws GeneralSecurityException {
    return ProtoKeySerialization.create(
        TYPE_URL,
        com.google.crypto.tink.proto.AesEaxKey.newBuilder()
            .setParams(getProtoParams(key.getParameters()))
            .setKeyValue(
                ByteString.copyFrom(
                    key.getKeyBytes().toByteArray(SecretKeyAccess.requireAccess(access))))
            .build()
            .toByteString(),
        KeyMaterialType.SYMMETRIC,
        toProtoOutputPrefixType(key.getParameters().getVariant()),
        key.getIdRequirementOrNull());
  }
Current implementation restricts to 16-byte tag value
java_src/src/main/java/com/google/crypto/tink/aead/internal/AesEaxProtoSerialization.java