public Builder addCoordinator(String nodeName) {
            if (coordinatorName != null) {
                throw new RuntimeException("At most one coordinator is allowed.");
            }
            coordinatorName = nodeName;
            return this;
        }
Add a new trogdor coordinator node to the cluster.
trogdor/src/test/java/org/apache/kafka/trogdor/common/MiniTrogdorCluster.java