This commit is a follow-on from 14c5ac0. It fixes a similar problem
with @AutoConfigureJsonTesters that is also apparent when using
@JsonTest.
Fixes gh-47811
The org.springframework.boot.test-auto-configuration plugin has been
added so that test auto-configuration imports files are checked at
build time, hopefully catching this sort of problem earlier in the
future.
Closes gh-47812
Stéphane Nicoll
Andy Wilkinson
Moritz Halbritter
Phillip Webb