code: @DontLabel
      public Rule anyOf(final char[] characters)
      {
          Objects.requireNonNull(characters);
          switch (characters.length) {
              case 0:
                  throw new IllegalArgumentException("empty character array");
              case 1:
                  return ch(characters[0]);
              default:
                  return anyOf(Characters.of(characters));
          }
      }
docs: Match any character in the given {@code char} array
  
  <p>This method delegates to {@link #anyOf(Characters)}.</p>
  
  @param characters the characters
  @return a rule
  
  @see #anyOf(Characters)