@Override
    final boolean isReusable() {
      return false;
    }
  }

  static final class NonTerminalImmutableBiMapEntry<K, V>
      extends NonTerminalImmutableMapEntry<K, V> {
    private final transient @Nullable ImmutableMapEntry<K, V> nextInValueBucket;

    NonTerminalImmutableBiMapEntry(
        K key,
        V value,
        @Nullable ImmutableMapEntry<K, V> nextInKeyBucket,