Utility classes commonly useful in concurrent programming.
 
 
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Returns a reverse order view of the mappings contained in this map. 
     ConcurrentNavigableMap.headMap(K toKey,
 boolean inclusive)
     ConcurrentSkipListMap.headMap(K toKey,
 boolean inclusive)
   ConcurrentNavigableMap.subMap(K fromKey,
 boolean fromInclusive,
 K toKey,
 boolean toInclusive)
   ConcurrentNavigableMap.subMap(K fromKey,
 K toKey)
   ConcurrentSkipListMap.subMap(K fromKey,
 boolean fromInclusive,
 K toKey,
 boolean toInclusive)
   ConcurrentSkipListMap.subMap(K fromKey,
 K toKey)
   ConcurrentNavigableMap.tailMap(K fromKey)
   ConcurrentNavigableMap.tailMap(K fromKey,
 boolean inclusive)
   ConcurrentSkipListMap.tailMap(K fromKey)
   ConcurrentSkipListMap.tailMap(K fromKey,
 boolean inclusive)