public interface HostProvider
A set of hosts a ZooKeeper client should connect to.
Classes implementing this interface must guarantee the following:
* Every call to next() returns an InetSocketAddress. So the iterator never
* The size() of a HostProvider may never be zero.
A HostProvider must return resolved InetSocketAddress instances on next() if the next address is resolvable.
In that case, it's up to the HostProvider, whether it returns the next resolvable address in the list or return
the next one as UnResolved.
Different HostProvider could be imagined:
* A HostProvider that loads the list of Hosts from an URL or from DNS
* A HostProvider that re-resolves the InetSocketAddress after a timeout.
* A HostProvider that prefers nearby hosts.