In order message delivery with async subscriber callbacks

[jackson-stone-ableto]

Say I publish messages 1, 2, and 3 in that order with the same ordering key within the same region, and I have some subscription set up to receive ordered messages, and the callback specified for that subscription is an async function that ack's at the end of the async function.

Will I still receive in the callback messages 2 and 3 if 1 has not yet finished it's async callback, even if I have not yet reached the ack deadline?

I'm not sure what doc may speak to this. The closest I could find was the second paragraph in the "Streaming Pull (Via the Client Libraries)" section of this blog post: https://medium.com/google-cloud/google-cloud-pub-sub-ordered-delivery-1e4181f60bc8 which made me suspect if I do anything async, I'm liable to get the next messages in my subscription callback potentially leading to race conditions in my callback's async function.