private static void validateVersion(int version) throws GeneralSecurityException {
    if (version != 0) {
      throw new GeneralSecurityException("Parsing failed: unknown version " + version);
    }
  }
Encodes a BigInteger using a big-endian encoding.
java_src/src/main/java/com/google/crypto/tink/jwt/JwtRsaSsaPkcs1ProtoSerialization.java