code: public synchronized void clearAllEntries() {
  
          tertiaryTable.putAll(primaryTable);
          tertiaryTable.putAll(secondaryTable);
  
          primaryTable.clear();
          secondaryTable.clear();
  
          evictStaleEntries();
      }
docs: Purge all entries from the Cache. Semantically, this should
  behave the same as the expiration of all entries from
  the cache.