@Contract(pure = true)
  public static @Unmodifiable @NotNull <K, V> Map<K, V> notNullize(@Nullable Map<K, V> map) {
    return map == null ? Collections.emptyMap() : map;
  }
@Contract(pure = true)
  public static @Unmodifiable @NotNull <K, V> Map<K, V> notNullize(@Nullable Map<K, V> map)