final protected JRTConnection pickNewConnectionRandomly(List<JRTConnection> sources) {
        return sources.get(ThreadLocalRandom.current().nextInt(0, sources.size()));
    }
Preconditions:
1. the current connection is unhealthy and should not be selected when switching
2. There is more than 1 source.
config/src/main/java/com/yahoo/vespa/config/JRTConnectionPool.java