Is there any way to pass the source from server to clients?

I've read the docs and found that I can pass some info to server by adding options.source in submitOp(), but how can a client get source from server?
My code looks like:
`
// client.ts
doc.submitSource = true;
doc.on("op batch", async (op, source) => {
console.log(source);
}
// opSubmit.ts

doc.submitSource = true;
let op: { p: [string, number]; sd?: string; si?: string }[] = [];
op.push({ p: ["content", offset], si: insertPosition});
doc.submitOp(op, {source: userId}); // userId is defined as string type, and I'm pretty sure I've passed a not-empty string value to it
`
However, the source output in client.ts turns out to be false(a boolean value). Are there any possible solutions I may try to make the codes work as I've expected?

Start by tracing the submitSource and "op batch" handling shown in client.ts and opSubmit.ts, then compare it with the documented submitOp source option. Verify whether the user-provided source reaches the client callback rather than being reported as false, and document or test the expected behavior.