Non-thread-safe usage of map can result in infinite loop and 100% CPU usage

From https://groups.google.com/forum/#!searchin/gwt-platform/spring/gwt-platform/vX2eKouqe74/dXDTZzuLB74J 
Recently we faced high CPU utilization by tomcat process running a GWTP and Spring based web-application. The thread dump shows several threads executing which stack-traces similar to following -

"http-443-2" daemon prio=10 tid=0x09d47000 nid=0x159e runnable [0x8cfd3000]
   java.lang.Thread.State: RUNNABLE
        at java.util.HashMap.get(Unknown Source)
        at com.gwtplatform.dispatch.server.spring.actionhandlervalidator.LazyActionHandlerValidatorRegistryImpl.findActionHandlerValidator(LazyActionHandlerValidatorRegistryImpl.java:68)
        at com.gwtplatform.dispatch.server.AbstractDispatchImpl.findHandler(AbstractDispatchImpl.java:196)
        at com.gwtplatform.dispatch.server.AbstractDispatchImpl.doExecute(AbstractDispatchImpl.java:147)
        at com.gwtplatform.dispatch.server.AbstractDispatchImpl.execute(AbstractDispatchImpl.java:111)
        at com.gwtplatform.dispatch.server.AbstractDispatchServiceImpl.execute(AbstractDispatchServiceImpl.java:81)

It seems that concurrent modifications to the maps used in this class may result in corrupted indexes [http://javaeesupportpatterns.blogspot.in/2012/02/hashmapget-high-cpu-case-study.html] in hashmap.