@Override
    public String computeMacAndEncode(RawJwt rawJwt) throws GeneralSecurityException {
      String unsignedCompact =
          JwtFormat.createUnsignedCompact(algorithm, jwtHmacKey.getKid(), rawJwt);
      return JwtFormat.createSignedCompact(
          unsignedCompact, mac.computeMac(unsignedCompact.getBytes(US_ASCII)));
    }
This key manager generates new {@code JwtHmacKey} keys and produces new instances of {@link
JwtHmac}.
java_src/src/main/java/com/google/crypto/tink/jwt/JwtHmacKeyManager.java