}

  /**
   * Returns an unmodifiable view of the specified map entry. The {@link Entry#setValue} operation
   * throws an {@link UnsupportedOperationException}. This also has the side effect of redefining
   * {@code equals} to comply with the Entry contract, to avoid a possible nefarious implementation
   * of equals.
   *
   * @param entry the entry for which to return an unmodifiable view