Use JDK 1.6's Collections.newSetFromMap instead of manually accessing Maps with dummy Boolean values
Added "destroyBean(Object)" method to AutowireCapableBeanFactory

Driven by the need for implementing Bean Validation 1.1's "releaseInstance" method in SpringConstraintValidatorFactory, as a direct counterpart to the use of AutowireCapableBeanFactory's "createBean(Class)" in "getInstance".

Issue: SPR-8199