In jitsi, I find that if it uses the distantPA, there also is one
PollOfflineContactsTask .But I think , the PollOfflineContactsTask is not
necessay when there is distantPA, because
the PA will record the subscription.
In RFC 3903,there is a example as below.Do jitsi implement this message
flow？（Because I have not implement the distant PA， I could not test it.）
<img src=’/uploads/jitsi/original/1X/0953efd2a1e880e51f705318743c6c6915ab998e.png’ width=‘449’ height=‘500’>
Beijing University of Posts and Telecommunications