public void testToString() {
    byte[] keyData = "secret key".getBytes(UTF_8);

    assertThat(hmacMd5(MD5_KEY).toString())
        .isEqualTo("Hashing.hmacMd5(Key[algorithm=HmacMD5, format=RAW])");
    assertThat(hmacMd5(keyData).toString())
        .isEqualTo("Hashing.hmacMd5(Key[algorithm=HmacMD5, format=RAW])");

    assertThat(hmacSha1(SHA1_KEY).toString())
        .isEqualTo("Hashing.hmacSha1(Key[algorithm=HmacSHA1, format=RAW])");

   * href="https://datatracker.ietf.org/doc/html/rfc6151#section-2.3">over {@code hmacMd5}</a>.
   *
   * @param key the secret key
   * @throws IllegalArgumentException if the given key is inappropriate for initializing this MAC
   * @since 20.0
   */
  public static HashFunction hmacMd5(Key key) {
    return new MacHashFunction("HmacMD5", key, hmacToString("hmacMd5", key));
  }

  /**