BinaryOperator<V> mergeFunction) {
    return CollectCollectors.toImmutableEnumMap(keyFunction, valueFunction, mergeFunction);
  }

  /**
   * Creates a <i>mutable</i>, empty {@code HashMap} instance.
   *
   * <p><b>Note:</b> if mutability is not required, use {@link ImmutableMap#of()} instead.
   *

          BinaryOperator<V> mergeFunction) {
    return CollectCollectors.toImmutableEnumMap(keyFunction, valueFunction, mergeFunction);
  }

  /**
   * Creates a <i>mutable</i>, empty {@code HashMap} instance.
   *
   * <p><b>Note:</b> if mutability is not required, use {@link ImmutableMap#of()} instead.
   *