Versioned.java

interface Versioned {
   long getVersion();
  
   void verifyVersion(Long version) default {
     if (version == null) return;
     if(getVersion() != version) throw new OptimisticLockFailureException("Unable to lock");
   }
   
   void setVersion(long version);
   
   long incrementVersion() default {
      long next = getVersion() + 1;
      setVersion(next);
      return next;
   }
}