@AccessesPartialKey
  private static RsaSsaPssPrivateKey toRsaSsaPssPrivateKey(
      com.google.crypto.tink.jwt.JwtRsaSsaPssPrivateKey privateKey)
      throws GeneralSecurityException {
    return RsaSsaPssPrivateKey.builder()
        .setPublicKey(JwtRsaSsaPssVerifyKeyManager.toRsaSsaPssPublicKey(privateKey.getPublicKey()))
        .setPrimes(privateKey.getPrimeP(), privateKey.getPrimeQ())
        .setPrivateExponent(privateKey.getPrivateExponent())
        .setPrimeExponents(privateKey.getPrimeExponentP(), privateKey.getPrimeExponentQ())
        .setCrtCoefficient(privateKey.getCrtCoefficient())
        .build();
  }
This key manager generates new {@code JwtRsaSsaPssPrivateKey} keys and produces new instances of
{@code JwtPublicKeySign}.
java_src/src/main/java/com/google/crypto/tink/jwt/JwtRsaSsaPssSignKeyManager.java