public class Commands {
    private Handlers handlers = new Handlers();

    private void bootstratap() {
        handlers.add(Deactivate.class, command -> deactivate(new ItemRepository(), command));
        handlers.add(Reactivate.class, command -> reactivate(new ItemRepository(), command));
        handlers.add(CheckIn.class, command -> log(command, () -> checkIn(new ItemRepository(), new BarService(), command)));
    }

    public static void deactivate(ItemRepository repository, Deactivate command) {
    }

    public static void reactivate(ItemRepository repository, Reactivate command) {
    }

    public static void checkIn(ItemRepository repository, BarService barService, CheckIn command) {
    }

    public static <T extends Command> void log(T command, Runnable next) {
        System.out.println("Going to call handler for " + command.getClass().getName());
        next.run();
    }
}

class Handlers {
    public <T extends Command> void add(Class<T> clazz, CommandHandler<T> handler) {
    }
}

interface CommandHandler <T extends Command> {
    void handle(T command);
}

class ItemRepository {}
class BarService {}
interface Command {}
class Deactivate implements Command {}
class Reactivate implements Command {}
class CheckIn implements Command {}