gunnarmorling/hibernate-validator — comment on commit 2f12e17f3e53ec86a66eeb15c3a0a54650be2e06
File: hibernate-validator/src/main/java/org/hibernate/validator/metadata/aggregated/BeanMetaDataImpl.java line 318
By hferentschik:

I think we need to synchronize this. Without synchronization it could happen that a second thread sees a non null descriptor reference, but the instance is not full constructed yet.