protected abstract @NonNull ConnectionConnectCohort connectionUp(@NonNull ConnectedClientConnection<T> newConn);
private void backendConnectFinished(final Long shard, final AbstractClientConnection<T> oldConn,
protected abstract @NonNull ConnectionConnectCohort connectionUp(@NonNull ConnectedClientConnection<T> newConn);
private void backendConnectFinished(final Long shard, final AbstractClientConnection<T> oldConn,