REST -> GET / | GET /?completed=[bool]

get.java

@Get
@Produces(MediaType.APPLICATION_JSON)
public Collection<Task> getTasks(@Nullable @QueryValue(value = "completed") Boolean completed)
    {
    Filter<Task> filter = completed == null
                          ? Filters.always()
                          : Filters.equal(Task::getCompleted, completed);

    return tasks.getAllOrderedBy(filter, Task::getCreatedAt);
    }