public History with(Event event) {
        ImmutableMap.Builder<Event.Type, Event> builder = builderWithout(event.type());
        builder.put(event.type(), event);
        List<Event> logCopy = new ArrayList<>(log);
        logCopy.add(event);
        return new History(builder.build(), logCopy, maxLogSize);
    }
Returns a copy of this history with the given event added
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/node/History.java