public void add(T node, boolean internal) {
        nodeMonitors.put(node, new TrafficNodeMonitor<>(node, configuration, internal));
    }
Adds a new node for monitoring.
The object representing the node must
<ul>
<li>Have a sensible toString</li>
<li>Have a sensible identity (equals and hashCode)</li>
</ul>

@param node the object representing the node
@param internal whether this node is internal to this cluster
container-search/src/main/java/com/yahoo/search/cluster/ClusterMonitor.java