@Contract(mutates = "param3")
  public static <K, V> void putIfNotNull(K key, @Nullable V value, @NotNull MultiMap<? super K, ? super V> result) {
    if (value != null) {
      result.putValue(key, value);
    }
  }
@Contract(mutates = "param3")
  public static <K, V> void putIfNotNull(K key, @Nullable V value, @NotNull MultiMap<? super K, ? super V> result)