final StringBuilder buf = new StringBuilder(pattern.length());
        for (int i = 0; i < pattern.length(); ++i) {
            final char ch = pattern.charAt(i);
            if (Character.isLetterOrDigit(ch) || Character.isWhitespace(ch)) {
                buf.append(ch);
            }
        }
        if (buf.indexOf("yy") == -1) {
            final int pos = buf.indexOf("y");
            if (pos != -1) {

  @Deprecated
  public static CharMatcher javaLetter() {
    return JavaLetter.INSTANCE;
  }

  /**
   * Determines whether a character is a BMP letter or digit according to {@linkplain
   * Character#isLetterOrDigit(char) Java's definition}.
   *
   * @deprecated Most letters and digits are supplementary characters; see the class documentation.
   * @since 19.0 (since 1.0 as constant {@code JAVA_LETTER_OR_DIGIT}).
   */