code: @Override
    public Set<Map.Entry<K, V>> entrySet() {
      if (lazyEntrySet == null) {
        lazyEntrySet = new EntrySet();
      }
      return lazyEntrySet;
    }
docs: Similar to the AbstractMap implementation of {@code keySet()} and
  {@code values()}, the entry set is created the first time this method is
  called, and returned in response to all subsequent calls.
  
  {@inheritDoc}