@Contract(pure = true)
  public static @NotNull String toHexString(byte @NotNull [] bytes) {
    String digits = "0123456789abcdef";
    StringBuilder sb = new StringBuilder(2 * bytes.length);
    for (byte b : bytes) {
      sb.append(digits.charAt((b >> 4) & 0xf)).append(digits.charAt(b & 0xf));
    }
    return sb.toString();
  }
@Contract(pure = true)
  public static @NotNull String toHexString(byte @NotNull [] bytes)