eplicaId</code>) and state-changes to one of them are replicated to the
        others so that they are eventually all in the same state.
        For this an
        <code>EventsourcedActor</code> defines the two methods:
    </p>
    <ul>
        <li><code>onCommand</code></li>
        <li><code>onEvent</code></li>
    </ul>
    <p>
        The purpose of <code>onCommand</code> is to process commands (of type
        <code>OrderCommand</code>) that sre sent to change
        the state of the order (like <c