Here's an interesting feedback from a customer:

http://stackoverflow.com/questions/38628150/gcloud-java-pubsub-api-how-to-set-return-immediately-flag

@mziccard @garrettjonesgoogle

Marco, what are your thoughts? And can you elaborate in this issue where this shows up in the code? It seems like this might cause some unnecessary polling.