[FIX] #636 박수 알림 누락 해결 및 플랫폼 유저 목록 조회 시 방어 로직 추가

src/main/java/org/sopt/app/application/platform/PlatformService.java

@@ -49,6 +49,10 @@ public PlatformUserInfoResponse getPlatformUserInfoResponse(Long userId) {
     public List<PlatformUserInfoResponse> getPlatformUserInfosResponse(List<Long> userIds) {
         final Map<String, String> headers = createAuthorizationHeader();
 
+        if(userIds == null || userIds.isEmpty()){
+            return Collections.emptyList();
+        }
+
         // 중복 제거
         userIds = userIds.stream().distinct().toList();
         final Map<String, String> params = createQueryParams(userIds);

src/main/java/org/sopt/app/application/stamp/ClapEventListener.java

@@ -30,7 +30,7 @@
 @RequiredArgsConstructor
 public class ClapEventListener {
 
-    private final RestTemplate restTemplate;
+    private final RestTemplate restTemplate = new RestTemplate();
     private final HttpHeadersUtils headersUtils;
 
     private final StampService stampService;

src/main/java/org/sopt/app/presentation/stamp/ClapRequest.java

@@ -40,12 +40,15 @@ public static class ClapAlarmRequest {
 		@Schema(description = "알림 제목")
 		@NotNull
 		private String title;
+
 		@Schema(description = "알림 내용")
 		@NotNull
 		private String content;
+
 		@Schema(description = "알림 카테고리")
 		@NotNull
 		private String category;
+
 		@Schema(description = "딥링크")
 		private String deepLink;