* @param lo the low surrogate pair character
   */
  public static void assertUnicodeEscaping(
      UnicodeEscaper escaper, String expected, char hi, char lo) {

    int cp = Character.toCodePoint(hi, lo);
    String escaped = computeReplacement(escaper, cp);
    Assert.assertNotNull(escaped);
    Assert.assertEquals(expected, escaped);
  }

   * @param lo the low surrogate pair character
   */
  public static void assertUnicodeEscaping(
      UnicodeEscaper escaper, String expected, char hi, char lo) {

    int cp = Character.toCodePoint(hi, lo);
    String escaped = computeReplacement(escaper, cp);
    Assert.assertNotNull(escaped);
    Assert.assertEquals(expected, escaped);
  }

          return -c1;
        }
        // Otherwise look for the low surrogate following it
        char c2 = seq.charAt(index);
        if (Character.isLowSurrogate(c2)) {
          return Character.toCodePoint(c1, c2);
        }
        throw new IllegalArgumentException(
            "Expected low surrogate but got char '"
                + c2
                + "' with value "
                + (int) c2