private static boolean hasExtension(@NotNull String fileName, @NotNull String extension, boolean caseSensitive) {
    if (fileName.length() < extension.length() + 1) return false;
    if (fileName.charAt(fileName.length() - extension.length() - 1) != '.') return false;
    return StringUtilRt.equal(fileName.subSequence(fileName.length() - extension.length(), fileName.length()), extension, caseSensitive);
  }
private static boolean hasExtension(@NotNull String fileName, @NotNull String extension, boolean caseSensitive)