docs: public static Payload decode(String base64) {
      JsonObject json = decodeToJson(base64);
      Payload payload = new Payload();
      json.keySet().forEach(key -> {
        switch (key) {
          case "iss":
            payload.issuer = json.getString(key);
            break;
          case "sub":
            payload.subject = json.getString(key);
            break;
          case "aud":
            payload.audience = json.getString(key);
            break;
          case "exp":
            payload.expires = new Long(json.get(key).toString());
            break;
          case "nbf":
            payload.notBefore = new Long(json.get(key).toString());
            break;
          case "iat":
            payload.issuedAt = new Long(json.get(key).toString());
            break;
          case "jti":
            payload.jwtId = json.getString(key);
            break;
          default:
            payload.add(key, json.getString(key));
        }
      });
      return payload;
    }