We've observed the following behavior in elections when a node is lagging behind the quorum in its view of the ensemble topology.
- Node A is operating with node B in its voting view, but without view of node C.
- B votes for C.
- A then switches its vote to C, but throws a NPE when attempting to connect.
This causes the QuorumPeer to spin up a Follower only to immediately have it shutdown by the exception.
Ideally, A would not advertise a vote for a server that it will not follow.