public Route setHop(int i, Hop hop) {
        cache = null;
        hops.set(i, hop);
        return this;
    }
<p>Sets the hop at a given index.</p>

@param i   The index at which to set the hop.
@param hop The hop to set.
@return This, to allow chaining.
messagebus/src/main/java/com/yahoo/messagebus/routing/Route.java