@Override
    public boolean equals(Object o) {
        if (o == this) return true;
        if ( ! (o instanceof ScalingEvent other)) return true;
        if ( other.generation != this.generation) return false;
        if ( ! other.at.equals(this.at)) return false;
        if ( ! other.from.equals(this.from)) return false;
        if ( ! other.to.equals(this.to)) return false;
        if ( ! other.completion.equals(this.completion)) return false;
        return true;
    }
Returns the time this event took to completion, or empty if it's not yet complete
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/applications/ScalingEvent.java