code: public void clear() {
      // Clears all keys, values and buckets linked lists.
      for (EntryImpl<K, V> entry = _mapFirst; entry != null; entry = entry._after) {
        entry._key = null;
        entry._value = null;
        entry._before = null;
        entry._next = null;
        if (entry._previous == null) { // First in bucket.
          _entries[entry._index] = null;
        } else {
          entry._previous = null;
        }
      }
  
      // Recycles all entries.
      if (_mapLast != null) {
        _mapLast._after = _poolFirst; // Connects to pool.
        _poolFirst = _mapFirst;
        _mapFirst = null;
        _mapLast = null;
        _size = 0;
        sizeChanged();
      }
    }
docs: Removes all mappings from this {@link FastMap}.