For messages with strange senders, we don't import
messages. Basically, we only import a message if
it has sender with an id that maps to a non-deleted
user.
Normal hipchat exports use integer ids for their
users and "rooms," which we just borrowed during
conversion.
Atlassian Stride uses stride UUIDs for these instead, but otherwise
has the same export format.
We now introduce IdMapper to handle external ids
that aren't integer. The IdMapper will map UUID
ids to ints and remember them. For ints it just
leaves them alone.
Fixes#10805.
These test are for the handling of HipChat
sender info. The data formats are somewhat
inconsistent and sometimes require us to
generate "mirror" users, so this is potentially
fragile code if we don't cover it well.
Steve Howell