private static ProtoParametersSerialization serializeParameters(
      JwtRsaSsaPssParameters parameters) throws GeneralSecurityException {
    OutputPrefixType outputPrefixType = toProtoOutputPrefixType(parameters);
    return ProtoParametersSerialization.create(
        KeyTemplate.newBuilder()
            .setTypeUrl(PRIVATE_TYPE_URL)
            .setValue(getProtoKeyFormat(parameters).toByteString())
            .setOutputPrefixType(outputPrefixType)
            .build());
  }
Encodes a BigInteger using a big-endian encoding.
java_src/src/main/java/com/google/crypto/tink/jwt/JwtRsaSsaPssProtoSerialization.java