# 값 타입에 목적지를 직접 넣어 무엇이 통과하는지 본다
    String[] endpoints = {
      "https://169.254.169.254/latest/meta-data/",
      "https://metadata.google.internal/computeMetadata/v1/",
      "https://10.0.0.5:8080/internal",
      "https://192.168.1.1/admin",
      "https://[fd00::1]/ula",
      "https://user:pw@evil.example.com/",
      "http://169.254.169.254/latest/meta-data/",
      "http://evil.example.com/x",
    };

통과  https://169.254.169.254/latest/meta-data/
통과  https://metadata.google.internal/computeMetadata/v1/
통과  https://10.0.0.5:8080/internal
통과  https://192.168.1.1/admin
통과  https://[fd00::1]/ula
통과  https://user:pw@evil.example.com/
거절  http://169.254.169.254/latest/meta-data/   -> endpoint must be https outside the loopback interface
거절  http://evil.example.com/x   -> endpoint must be https outside the loopback interface

# 이웃 호출처는 같은 결함을 이미 고쳤고, 고치면서 무엇이 남았는지 적었다
    // requireExternallyRoutable, not requireSecureOrLoopback. The scheme check accepted any HTTPS
    // URL, so `https://169.254.169.254/` — the cloud metadata service — and every RFC 1918 address
    // passed. The stronger guard was written for exactly this call site and then called from
    // nowhere: it existed, its own tests were green, and the two sites it was written for kept the
    // weaker check.

# 그 엔드포인트가 가는 곳
113:    return new NotificationHttpRequest(
114-        "POST",
115-        subscription.endpoint(),
116-        JdkNotificationHttpGateway.headers(headers),

# 그 값을 만드는 main 코드 — 저장이 아니라 저장된 것을 되읽는 경로다
AesGcmContactPointProtector.java:217:    return new WebPushSubscriptionValue(
64:  public ProtectedContactPoint protect(ContactPointValue value) {
86:  public ContactPointValue reveal(ProtectedContactPoint protectedValue, AccessContext context) {
210:  private static WebPushSubscriptionValue parseWebPush(String stored) {
# 접수 유스케이스는 그 채널을 주소 문자열로 받지 않는다
      case EMAIL -> EmailAddress.parse(address);
      case SMS -> new PhoneNumber(address);
      case IN_APP -> new InAppRecipientRef(address);
      case PUSH, WEB_PUSH, WEBHOOK ->
          throw new IllegalArgumentException(
              "channel "
                  + channel
# 알림 플랫폼 마스터 스위치의 출하 기본값
486:      enabled: ${APP_NOTIFICATION_PLATFORM_ENABLED:false}