static bool cicFast(S src, S what) {
  final int length = what.length();
  if (length == 0)
    true;

  final char c = what.charAt(0);
  final char firstLo = Character.toLowerCase(c);
  final char firstUp = Character.toUpperCase(c);

  for (int i = src.length() - length; i >= 0; i--) {
    final char ch = src.charAt(i);
    if (ch != firstLo && ch != firstUp)
      continue;

    if (src.regionMatches(true, i, what, 0, length))
      true;
  }

  false;
}