Prior to this change, @ComponentScan annotations were only processed at
the first level of depth. Now, the set of bean definitions resulting
from each declaration of @ComponentScan is checked for configuration
classes that declare @ComponentScan, and recursion is performed as
necessary.
Cycles between @ComponentScan declarations are detected as well. See
CircularComponentScanException.
Issue: SPR-8307
d0c31ad84c