code: @Override
      public final V getOrDefault(Object key, V defaultValue) {
          long hash, allocIndex;
          Segment<K, V> segment;
          return (allocIndex = (segment = segment(segmentIndex(hash = keyHashCode(key))))
                  .find(this, hash, key)) > 0 ?
                  segment.readValue(allocIndex) : defaultValue;
      }
docs: Returns the value to which the specified key is mapped, or {@code defaultValue} if this map
  contains no mapping for the key.
  
  @param key the key whose associated value is to be returned
  @param defaultValue the default mapping of the key
  @return the value to which the specified key is mapped, or {@code defaultValue} if this map
  contains no mapping for the key