Initialization ordering

[lburgazzoli]

I have a component that tries to lookup a reference to a bean from the registry - thus from ArC - as following:

@Override
protected void doInit() throws Exception {
    super.doInit();

    if (this.vertx == null) {
        Set<Vertx> instances = getCamelContext().getRegistry().findByType(Vertx.class);
        if (instances.size() == 1) {
            this.vertx = instances.iterator().next();

            if (this.vertx != null) {
                LOGGER.info("Found Vert.x instance in registry: {}", this.vertx);
            }
        }
    }
}

and it turn out that ArC could find a bean of the given type but fails to resolve the reference so findByType returns a collection with a single element as expected but then the element is null.

This happens because the lookup method inside the came registry happens before the Vertx producer is properly initialized.

As initializing components from bean auto-discovered from registry is quite a common and powerful feature we need a better way to deal with dependencies, maybe we should not automatically populate the registry with components/languages/dataformat but we need to delegate this to the actual extension that can properly set-up dependencies on other extensions.

i.e. we can create {Component|DataFormat|Language}BuildItem and populate the registry from such items.

//cc @gnodet @davsclaus

[lburgazzoli]

With PR #148 I've added basic support for defining object to be bound to the camel context so you can do something like:

@Recorder
public class SupportRecorder {
    CamelRegistryBuildItem logComponent() {
        DefaultExchangeFormatter def = new DefaultExchangeFormatter();
        def.setShowAll(true);
        def.setMultiline(true);

        LogComponent component = new LogComponent();
        component.setExchangeFormatter(def);

        return new CamelRegistryBuildItem(
            "log",
            LogComponent.class,
            component
        );
    }
}

public class SupportBuildStep {
    @Record(ExecutionTime.STATIC_INIT)
    @BuildStep
    CamelRegistryBuildItem logComponent(SupportRecorder recorder) {
        return recorder.logComponent();
    }
}

And the pre-configured log component will be put in camel registry.

[lburgazzoli]

Done in #148