@Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Node node = (Node) o;
        return index == node.index;
    }
Returns the unique index of this node in the cluster.
Indices are non-negative, but not necessarily contiguous or starting from zero.
hosted-zone-api/src/main/java/ai/vespa/cloud/Node.java