StringBuilder buf = new StringBuilder();
        Supplier<Object> supplier = () -> "test \"quotes\" and \n newline";

        monitorTarget.append(buf, "specialKey", supplier);
        assertEquals("\"specialKey\":\"test \\\"quotes\\\" and \\n newline\"", buf.toString());
    }

    // Test append method with String containing backslash
    public void test_append_stringWithBackslash() {

        return appendFileterPath(buf, escape(s));
    }

    /**
     * Escapes special regex characters in a string to create a literal pattern.
     * Handles anchor characters (^ and $) specially to preserve their regex meaning.
     *
     * @param s the string to escape
     * @return an escaped regex pattern, or empty string for comments
     */
    protected String escape(final String s) {

   *
   * @return Is the domain name syntactically valid?
   */
  private static boolean validateSyntax(List<String> parts) {
    int lastIndex = parts.size() - 1;

    // Validate the last part specially, as it has different syntax rules.

    if (!validatePart(parts.get(lastIndex), true)) {
      return false;
    }

    for (int i = 0; i < lastIndex; i++) {
      String part = parts.get(i);