code: public static <K, V> ConcurrentMap<K, V> createConcurrentHashMap(int expectedMapSize) {
          //concurrent hash map will size itself to accomodate this many elements
          return new ConcurrentHashMap<K, V>(expectedMapSize);
      }
docs: Utility method that creates an {@link java.util.LinkedHashMap} with its initialCapacity calculated
  to minimize rehash operations