Context ctx = RequestHeaders.withHeader(Context.current(), "x-request-id", "abc-123");
ctx.run(() -> client.listCollectionsAsync());

Map<String, String> headers = new HashMap<>();
headers.put("x-request-id", "abc-123");
headers.put("x-tenant-id", "org-456");

Context ctx = RequestHeaders.withHeaders(Context.current(), headers);
ctx.run(() -> {
    client.upsertAsync("my-collection", points);
    client.queryAsync("my-collection", searchRequest, 10);
    // both carry x-request-id
});