How to use the node-opcua-common.SessionDiagnosticsDataType function in node-opcua-common

}
});

ServerSession.prototype.__defineGetter__("addressSpace", function () {
    return this.parent ? this.parent.addressSpace : null;
});

ServerSession.prototype.__defineGetter__("currentPublishRequestInQueue", function () {
    const self = this;
    return self.publishEngine ? self.publishEngine.pendingPublishRequestCount : 0;
});

//xx ServerSession.prototype.__defineGetter__("serverDiagnostics")

const ServiceCounterDataType = require("node-opcua-common").ServiceCounterDataType;
const SessionDiagnosticsDataType = require("node-opcua-common").SessionDiagnosticsDataType;
const SubscriptionDiagnosticsDataType = require("node-opcua-common").SubscriptionDiagnosticsDataType;


ServerSession.prototype.updateClientLastContactTime = function (currentTime) {
    const session = this;
    if (session._sessionDiagnostics && session._sessionDiagnostics.clientLastContactTime) {
        currentTime = currentTime || new Date();
        // do not record all ticks as this may be overwhelming,
        if (currentTime.getTime() - 250 >= session._sessionDiagnostics.clientLastContactTime.getTime()) {
            session._sessionDiagnostics.clientLastContactTime = currentTime;
        }
    }
};


/**

const SubscriptionState = new Enum([
    "CLOSED",   // The Subscription has not yet been created or has terminated.
    "CREATING", // The Subscription is being created
    "NORMAL",   // The Subscription is cyclically checking for Notifications from its MonitoredItems.
                // The keep-alive counter is not used in this state.
    "LATE",     // The publishing timer has expired and there are Notifications available or a keep-alive Message is
                // ready to be sent, but there are no Publish requests queued. When in this state, the next Publish
                // request is processed when it is received. The keep-alive counter is not used in this state.
    "KEEPALIVE",// The Subscription is cyclically checking for Notification
                // alive counter to count down to 0 from its maximum.
    "TERMINATED"
]);
exports.SubscriptionState = SubscriptionState;


const SessionDiagnosticsDataType = require("node-opcua-common").SessionDiagnosticsDataType;


function _adjust_publishing_interval(publishingInterval) {
    publishingInterval = publishingInterval || Subscription.defaultPublishingInterval;
    publishingInterval = Math.max(publishingInterval, Subscription.minimumPublishingInterval);
    publishingInterval = Math.min(publishingInterval, Subscription.maximumPublishingInterval);
    return publishingInterval;
}

const minimumMaxKeepAliveCount = 2;
const maximumMaxKeepAliveCount = 12000;

function _adjust_maxKeepAliveCount(maxKeepAliveCount/*,publishingInterval*/) {
    maxKeepAliveCount = maxKeepAliveCount || minimumMaxKeepAliveCount;
    maxKeepAliveCount = Math.max(maxKeepAliveCount, minimumMaxKeepAliveCount);
    maxKeepAliveCount = Math.min(maxKeepAliveCount, maximumMaxKeepAliveCount);