@Nonnull
    public static <T extends Event> SingleSubscriptionBuilder<T> subscribe(@Nonnull Class<T> eventClass) {
        return SingleSubscriptionBuilder.newBuilder(eventClass);
    }
Makes a SingleSubscriptionBuilder for a given event

@param eventClass the class of the event
@param <T>        the event type
@return a {@link SingleSubscriptionBuilder} to construct the event handler
@throws NullPointerException if eventClass is null
helper/src/main/java/me/lucko/helper/Events.java