@Contract(pure = true)
  public static int indexOfIgnoreCase(@NotNull CharSequence where, @NotNull CharSequence what, int fromIndex) {
    int targetCount = what.length();
    int sourceCount = where.length();

    if (fromIndex >= sourceCount) {
      return targetCount == 0 ? sourceCount : -1;
    }

    if (fromIndex < 0) {
      fromIndex = 0;
    }

    if (targetCount == 0) {
      return fromIndex;
    }

    char first = what.charAt(0);
    int max = sourceCount - targetCount;

    for (int i = fromIndex; i <= max; i++) {
      /* Look for first character. */
      if (!charsEqualIgnoreCase(where.charAt(i), first)) {
        //noinspection StatementWithEmptyBody,AssignmentToForLoopParameter
        while (++i <= max && !charsEqualIgnoreCase(where.charAt(i), first)) ;
      }

      /* Found first character, now look at the rest of v2 */
      if (i <= max) {
        int j = i + 1;
        int end = j + targetCount - 1;
        //noinspection StatementWithEmptyBody
        for (int k = 1; j < end && charsEqualIgnoreCase(where.charAt(j), what.charAt(k)); j++, k++) ;

        if (j == end) {
          /* Found whole string. */
          return i;
        }
      }
    }

    return -1;
  }
@Contract(pure = true)
  public static int indexOfIgnoreCase(@NotNull CharSequence where, @NotNull CharSequence what, int fromIndex)