For syncing streams between Zephyr and Zulip, we need to be able to
have the API client send the server a long list of streams, some of
which might be invite-only, and add the ones that it can add and not
the ones it cannot without a bunch of annoying round trips dropping
individual streams one is not authorized to one by one. This argument
makes that possible.
We might find other applications as well.
(imported from commit 9236d185897c42218ab6cac3d8f3ddcb1bbc94e9)