SecretKey customKey =
        new SecretKey() {
          @Override
          public String getAlgorithm() {
            return "HmacMD5";
          }

          @Override
          public byte[] getEncoded() {
            return new byte[8];
          }

          @Override
          public String getFormat() {
            return "RAW";
          }
        };
    assertThat(