* Even if empty string, treated as empty plainly. So "IF pmb != null" is false if empty.
     * @param clustername The parameter value of clustername. (NotNull)
     */
    public void setClustername(String clustername) {
        registerVariable("clustername", clustername);
    }

    /**
     * Set the value of clusterstatus, used in parameter comment. <br>

                    .append(ping.getClusterName())
                    .append(" is changed to ")
                    .append(ping.getClusterStatus())
                    .append('.');
        } else if (status == 0) {
            resultBuf.append(ping.getClusterName()).append(" is alive.");
        } else {
            resultBuf.append(ping.getClusterName()).append(" is not available.");
        }

     */
    public PingResponse(final ClusterHealthResponse response) {
        status = response.getStatus() == ClusterHealthStatus.RED ? 1 : 0;
        clusterName = response.getClusterName();
        clusterStatus = response.getStatus().toString();
        final Set<String> fieldSet = ComponentUtil.getFessConfig().getApiPingEsFieldSet();

                    .setTimeout(timeout)
                    .setType(type)
                    .execute()
                    .actionGet(timeout);
            append(buf, "cluster_name", () -> response.getClusterName().value()).append(',');
            final String hotThreads = response.getNodesMap().entrySet().stream().map(e -> {
                final StringBuilder tempBuf = new StringBuilder();