Add support for Batch transactions (XLS-56d)

[sappenin]

See XLS-56d spec for more details.

If you would like to see support for this feature added into xrpl4j, please comment here in this ticket.

[VLEFF]

Well, I found this issue just after creating the same...
I'm here to comment and ask support for this feature!

[sappenin]

Hello @VLEFF, thanks for your message!

We're currently working to add support into xrpl4j for Credentials, Permissioned Domains, and Permissioned DEX. After that, the plan is to add Batch support (But I don't have a firm ETA at present).

[VLEFF]

Hello, any news about this feature?

[sappenin]

Hi @VLEFF - thanks for the ping. It looks like we're targeting mid-January 2026 to work on this issue. Does that timing work OK on your end?

(of course, PRs are always welcome if you want to try and implement this before the timing above. I'm always happy to review in that case sooner than January)

[VLEFF]

Hello @sappenin

Sorry for the late answer,
I have started looking into your work for batches, and it's working great.
I already had some custom implementation for batching transactions, and the switch has been flawless.

One little detail I would change is for the inner tx signingPublicKey, which should be "" (empty string).

//Working

paymentBuilder.signingPublicKey(PublicKey.builder().value(UnsignedByteArray.empty()).build()); 
paymentBuilder.signingPublicKey(PublicKey.fromBase58EncodedPublicKey(""));
paymentBuilder.signingPublicKey(PublicKey.fromBase16EncodedPublicKey(""));

//Not Working (null check for value)
paymentBuilder.signingPublicKey(PublicKey.builder().build());

Maybe a dedicated function could be better for lisibility, like :

paymentBuilder.signingPublicKey(PublicKey.empty());
or
paymentBuilder.signingPublicKey(PublicKey.batchInnerTransaction());

[sappenin]

Thanks for your suggestion! I'll take a look and report back.

[sappenin]

One little detail I would change is for the inner tx signingPublicKey, which should be "" (empty string).

So, I think this request is somewhat orthogonal to Batch (it's not an issue with the Payment builder, but actually an issue in the PublicKey builder instead).

I've created #683 to track it, and have a draft PR (see #684). Want to give that issue + PR a quick look over?

[sappenin]

This is complete as of #653, #654, and #676. We'll make a new v6.1 release with this hopefully today.