}

    private static <K, V extends @Nullable Object> Iterator<Entry<K, V>> transformEntries(
        Iterator<Entry<K, V>> entries) {
      return Iterators.transform(entries, UnmodifiableEntry::new);
    }

    private UnmodifiableEntry(Entry<K, V> delegate) {
      this.delegate = checkNotNull(delegate);
    }

    @Override
    protected Entry<K, V> delegate() {
      return delegate;
    }