The current code would work just fine for a connection having
multiple endpoints. However, when there is only one endpoint
ConnectionAttemptState.nextAddress() would return null, since
connectionEndpointIterator has already iterated over the only
possible value in the contructor leading to a NullPointerException.
This means that during establishment of a connection having multiple
endpoints, the first value inside connectionEndpointIterator would
always be overlooked.
This continues the design started with e98d42790 ("SmackReactor/NIO,
Java8/Android19, Pretty print XML, FSM connections"), where the
exceptions that caused an operation to fail, are not recorded within
SynchronizationPoint but within the connection instance itself.
This is a complete redesign of what was previously
XmppNioTcpConnection. The new architecture allows to extend an XMPP
client to server (c2s) connection with new transport bindings and
other extensions.