* Adds JavaDoc to `AbstractWireTestCase` and
`AbstractWireSerializingTestCase` so it is more obvious you should prefer
the latter if you have a choice
* Moves the `instanceReader` method out of `AbstractWireTestCase` becaue
it is no longer used.
* Marks a bunch of methods final so it is more obvious which classes are
for what.
* Cleans up the side effects of the above.
2362c430cd