code: public static JsonWebKey fromAes(SecretKey secretKey) {
          if (secretKey == null) {
              return null;
          }
  
          return new JsonWebKey().withK(secretKey.getEncoded()).withKty(JsonWebKeyType.OCT);
      }
docs: Converts AES key to JSON web key.
  
  @param secretKey
  AES key
  @return the JSON web key, converted from AES key.