# 첫 가드가 SINGLE 아닌 전략을 전부 거부한다
  private static void validateRouteShape(NotificationRouteDescriptor route) {
    if (route.routeStrategy()
        != dev.caskeleton.application.notification.NotificationRouteStrategy.SINGLE) {
      throw new NotificationCatalogException(
          "initial notification catalog supports SINGLE route strategy only");
    }
#   그 뒤 전략을 보지 않는 검사 둘
    if (route.targets().size() != route.maximumTargets()) {
      throw new NotificationCatalogException(
          "route target count must equal its maximum target bound");
    }
    long worstCaseCalls =
        Math.addExact(
            Math.multiplyExact(
                (long) route.maximumTargets(), (long) route.maximumPhysicalAttempts()),
            route.maximumReconcileCalls());
    if (worstCaseCalls > route.maximumTotalProviderCalls()) {
      throw new NotificationCatalogException(
          "route amplification exceeds maximum total provider calls");
    }

# switch 네 갈래 — SINGLE 을 뺀 셋은 도달할 수 없다
    switch (route.routeStrategy()) {
      case SINGLE -> {
        if (route.maximumTargets() != 1
            || route.maximumFallbackActivations() != 0
            || route.targets().stream().anyMatch(target -> target.fallbackTargetId().isPresent())) {
          throw new NotificationCatalogException(
              "SINGLE route requires one target and no fallback");
        }
      }
      case FAN_OUT_ALL -> {
        if (route.maximumFallbackActivations() != 0
            || route.targets().stream().anyMatch(target -> target.fallbackTargetId().isPresent())) {
          throw new NotificationCatalogException("FAN_OUT_ALL route cannot define fallback");
        }
      }
      case ORDERED_FALLBACK -> {
        if (route.maximumTargets() < 2
            || route.maximumFallbackActivations() < 1
            || route.maximumFallbackActivations() > route.maximumTargets() - 1) {
          throw new NotificationCatalogException("ORDERED_FALLBACK route has invalid bounds");
        }
      }
      default ->
          throw new NotificationCatalogException(
              "unknown notification route strategy: " + route.routeStrategy());
    }
    validateFallbackGraph(route);

# 그리고 폴백 그래프 검사가 던질 수 있는 두 문구
204:                                "fallback references unknown target");
213:          throw new NotificationCatalogException("cyclic notification fallback graph");

# 순환을 거부한다는 테스트
189:  void legacyReceiptUnsafeFallbackBoundsAndCyclesAreRejected() {
#   그 테스트가 만든 팬아웃 라우트
    NotificationRouteDescriptor unsupportedFanOut =
        new NotificationRouteDescriptor(
            new NotificationRouteId("security-slack"),
            3,
            NotificationChannel.SLACK,
            NotificationMode.DURABLE_ASYNC,
            NotificationAdmissionClass.TRANSACTIONAL,
            NotificationRouteStrategy.FAN_OUT_ALL,
#   그리고 순환 라우트 — 전략과 범위 값
    NotificationRouteDescriptor cyclic =
        new NotificationRouteDescriptor(
            new NotificationRouteId("security-slack"),
            3,
            NotificationChannel.SLACK,
            NotificationMode.DURABLE_ASYNC,
            NotificationAdmissionClass.TRANSACTIONAL,
            NotificationRouteStrategy.ORDERED_FALLBACK,
            new NotificationTemplateRef("security-slack", 1),
            false,
            false,
            2,
            1,
            1,
            0,
            2,
            Duration.ofSeconds(5),
            List.of(
                new NotificationRouteDescriptor.Target(
                    "target-a", "slack-runtime-r1", Optional.of("target-b")),
                new NotificationRouteDescriptor.Target(
                    "target-b", "slack-runtime-r1", Optional.of("target-a"))));
#   그 둘에 붙은 단언
175:        .hasMessageContaining("explicit active revision");
211:        .hasMessageContaining("legacy");

# 이 두 분기를 태울 라우트를 만드는 곳 — 저장소 전수
NotificationKindPolicyTest.java:44:            NotificationRouteStrategy.FAN_OUT_ALL);
NotificationKindPolicyTest.java:76:                    NotificationRouteStrategy.FAN_OUT_ALL,
NotificationKindPolicyTest.java:105:        strategy == NotificationRouteStrategy.ORDERED_FALLBACK ? 1 : 0,
NotificationKindPolicy.java:115:    if (strategy == NotificationRouteStrategy.FAN_OUT_ALL && maximumFallbacks != 0) {
NotificationKindPolicy.java:118:    if (strategy == NotificationRouteStrategy.ORDERED_FALLBACK
NotificationBindingCompilerTest.java:253:            NotificationRouteStrategy.FAN_OUT_ALL,
NotificationBindingCompilerTest.java:286:            NotificationRouteStrategy.ORDERED_FALLBACK,
#   설정 파일의 비-SINGLE 전략: 0

# 그 테스트를 실제로 돌린 결과
BUILD SUCCESSFUL in 1s
tests="5" skipped="0" failures="0" errors="0"