fix: Add missing syncronizations to PacketCache. (#360)
fix: Add missing syncronizations to PacketCache. (#360)

Fixes a ConcurrentModificationException observed in jvb when endpoints expire
jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,jitsi/jitsi-videobridge,jitsi/jitsi-videobridge