Stuck threads at
(self-tuning)'" #262 daemon prio=1 os_prio=0 tid=0x00007f1480091000
nid=0x187a runnable [0x00007f1456863000]
java.lang.Thread.State: RUNNABLE
at java.util.WeakHashMap.get(WeakHashMap.java:403)
at
javax.validation.Validation$GetValidationProviderListAction.getCachedValidatio

nProviders(Validation.java:368)

• locked <0x00000005f44e3e10> (a
  javax.validation.Validation$GetValidationProviderListAction)
  at
  javax.validation.Validation$GetValidationProviderListAction.run(Validation.jav

a:323)
at
javax.validation.Validation$GetValidationProviderListAction.getValidationProvi

derList(Validation.java:316)
at
javax.validation.Validation$DefaultValidationProviderResolver.getValidationPro

viders(Validation.java:299)

this is because WeakHashMap is not synchronized