protected T getFirstConnection(NodeList<T> nodes, int code, int trynum, Query query) {
        return nodes.select(code, trynum);
    }
Pings this connection. Pings may be sent "out of band" at any time by the
monitoring subsystem to determine the status of this connection. If the
ping fails, it is ok both to set an error in the pong or to throw an
exception.
container-search/src/main/java/com/yahoo/search/cluster/ClusterSearcher.java