@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (!(o instanceof NodeGroup nodeGroup)) return false;
        return Objects.equals(application, nodeGroup.application) &&
                Objects.equals(hostNames, nodeGroup.hostNames);
    }
A group of nodes belonging to the same application instance.
orchestrator/src/main/java/com/yahoo/vespa/orchestrator/model/NodeGroup.java