public static CharMatcher invisible() {
    return Invisible.INSTANCE;
  }

  /**
   * Determines whether a character is single-width (not double-width). When in doubt, this matcher
   * errs on the side of returning {@code false} (that is, it tends to assume a character is
   * double-width).
   *
   * <p><b>Note:</b> as the reference file evolves, we will modify this matcher to keep it up to
   * date.
   *

  public static CharMatcher invisible() {
    return Invisible.INSTANCE;
  }

  /**
   * Determines whether a character is single-width (not double-width). When in doubt, this matcher
   * errs on the side of returning {@code false} (that is, it tends to assume a character is
   * double-width).
   *
   * <p><b>Note:</b> as the reference file evolves, we will modify this matcher to keep it up to
   * date.
   *

    Integer getThumbnailHtmlImageMinHeightAsInteger();

    java.math.BigDecimal getThumbnailHtmlImageMaxAspectRatioAsDecimal();

    default boolean validateThumbnailSize(final int width, final int height) {
        if (width <= 0 || height <= 0 || width < getThumbnailHtmlImageMinWidthAsInteger().intValue()
                || height < getThumbnailHtmlImageMinHeightAsInteger().intValue()) {
            return false;
        }

    // hair space
    assertThat(parse("http://h/\u200a").encodedPath).isEqualTo("/%E2%80%8A")
    // zero-width space
    assertThat(parse("http://h/\u200b").encodedPath).isEqualTo("/%E2%80%8B")
    // zero-width non-joiner
    assertThat(parse("http://h/\u200c").encodedPath).isEqualTo("/%E2%80%8C")
    // zero-width joiner
    assertThat(parse("http://h/\u200d").encodedPath).isEqualTo("/%E2%80%8D")
    // left-to-right mark