fix(gateway): Spring 6.2 + Base64 API migrations (ResponseCookie, statusCode, encodeToString, orElseThrow, effectively-final)

- CasdoorOauthController: stateCookie -> ResponseCookie (HttpCookie.builder removed in 6.2),
  B64URL encoder/decoder split, encodeBytes -> encodeToString
- CasdoorClient: resp.status() -> resp.statusCode()
- CasdoorIdTokenVerifier: Optional.orElseThrow in map (type witness), no ternary+Mono.error
- CasdoorUserService: throw instead of Mono.error inside fromCallable (type inference)
- AuthFilter: effectively-final local for lambda capture

backend/api-gateway/src/main/java/com/deepdata/gateway/common/filter/AuthFilter.java

@@ -90,10 +90,11 @@ public class AuthFilter implements GlobalFilter, Ordered {
                 ssoUser = request.getHeaders().getFirst("X-User-Name");
             }
             if (StringUtils.isNotBlank(ssoUser)) {
+                final String ssoUserFinal = ssoUser;
                 log.info("SSO mode detected, adding User header: {}", ssoUser);
                 ServerHttpRequest mutatedRequest = request.mutate()
                         .headers(httpHeaders -> {
-                            httpHeaders.set(USER_HEADER, ssoUser);
+                            httpHeaders.set(USER_HEADER, ssoUserFinal);
                         })
                         .build();
                 ServerWebExchange mutatedExchange = exchange.mutate()

backend/api-gateway/src/main/java/com/deepdata/gateway/infrastructure/casdoor/CasdoorClient.java

@@ -122,7 +122,7 @@ public class CasdoorClient {
     }
 
     private Mono<String> errorBody(ClientResponse resp) {
-        return resp.bodyToMono(String.class).defaultIfEmpty(resp.status().toString());
+        return resp.bodyToMono(String.class).defaultIfEmpty(resp.statusCode().toString());
     }
 
     private static String enc(String s) {

backend/api-gateway/src/main/java/com/deepdata/gateway/infrastructure/casdoor/CasdoorIdTokenVerifier.java

@@ -119,11 +119,10 @@ public class CasdoorIdTokenVerifier {
                                 "id_token kid not found in JWKS after refresh"));
                     }
                     return loadKeys(true)
-                            .flatMap(k2 -> Optional.ofNullable(parseWithKid(idToken, k2)))
-                            .flatMap(o2 -> o2.isPresent()
-                                    ? Mono.just(o2.get())
-                                    : Mono.error(new CasdoorIdTokenException(
-                                    "id_token kid not found in JWKS after refresh")));
+                            .map(k2 -> Optional.ofNullable(parseWithKid(idToken, k2)))
+                            .map(o2 -> o2.<CasdoorIdTokenException>orElseThrow(() ->
+                                    new CasdoorIdTokenException(
+                                            "id_token kid not found in JWKS after refresh")));
                 });
     }
 

backend/api-gateway/src/main/java/com/deepdata/gateway/infrastructure/casdoor/CasdoorUserService.java

@@ -62,8 +62,7 @@ public class CasdoorUserService {
             User user = findByUsername(username);
             if (user != null) {
                 if (!user.isEnabled()) {
-                    return Mono.error(new CasdoorProvisionException(
-                            "local user disabled: " + username));
+                    throw new CasdoorProvisionException("local user disabled: " + username);
                 }
                 user.setLastLoginAt(now);
                 if (hasText(claims.email()) && !claims.email().equals(user.getEmail())) {
@@ -74,8 +73,8 @@ public class CasdoorUserService {
                 return new ProvisionedUser(user, userService.generateToken(user), false);
             }
             if (!props.isAutoProvision()) {
-                return Mono.error(new CasdoorProvisionException(
-                        "local user not found and auto-provision disabled: " + username));
+                throw new CasdoorProvisionException(
+                        "local user not found and auto-provision disabled: " + username);
             }
             User created = createUser(claims, username, now);
             try {

backend/api-gateway/src/main/java/com/deepdata/gateway/interfaces/rest/CasdoorOauthController.java

@@ -11,6 +11,7 @@ import lombok.extern.slf4j.Slf4j;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
 import org.springframework.http.HttpCookie;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseCookie;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
@@ -64,6 +65,7 @@ public class CasdoorOauthController {
 
     private static final SecureRandom RANDOM = new SecureRandom();
     private static final Base64.Encoder B64URL = Base64.getUrlEncoder().withoutPadding();
+    private static final Base64.Decoder B64URL_DEC = Base64.getUrlDecoder();
 
     private final CasdoorProperties props;
     private final CasdoorClient casdoorClient;
@@ -75,8 +77,8 @@ public class CasdoorOauthController {
     public Mono<ResponseEntity<Void>> login(@RequestParam(name = "next", required = false) String next,
                                             ServerWebExchange exchange) {
         String safeNext = sanitizeNext(next);
-        String state = B64URL.encodeBytes(randomBytes(32));
-        String cookieValue = state + "." + B64URL.encodeBytes(safeNext.getBytes(StandardCharsets.UTF_8));
+        String state = B64URL.encodeToString(randomBytes(32));
+        String cookieValue = state + "." + B64URL.encodeToString(safeNext.getBytes(StandardCharsets.UTF_8));
 
         exchange.getResponse().addCookie(
                 stateCookie(cookieValue, Duration.ofSeconds(props.getStateTtlSeconds())));
@@ -184,7 +186,7 @@ public class CasdoorOauthController {
 
     private static String decodeNext(String encoded) {
         try {
-            return new String(B64URL.decode(encoded), StandardCharsets.UTF_8);
+            return new String(B64URL_DEC.decode(encoded), StandardCharsets.UTF_8);
         } catch (IllegalArgumentException e) {
             return "/";
         }
@@ -201,8 +203,8 @@ public class CasdoorOauthController {
         return cookie == null ? null : cookie.getValue();
     }
 
-    private HttpCookie stateCookie(String value, Duration maxAge) {
-        HttpCookie.Builder builder = HttpCookie.builder(props.getStateCookieName());
+    private ResponseCookie stateCookie(String value, Duration maxAge) {
+        ResponseCookie.ResponseCookieBuilder builder = ResponseCookie.from(props.getStateCookieName());
         if (value != null) {
             builder.value(value);
         }