Build a Tiny Container

What does a container actually do between the start of the program and the moment BookingService is ready to use? It has no list of wiring lines to follow. It has only the classes themselves, and from those it must work out what to create, in which order, and how many copies to keep.

The answer fits in a small amount of plain Java. Writing that Java once makes the real container much easier to reason about, so the sections below build a container of about 55 lines, run it on the booking service, and then compare it with what Spring does.