Add SpnegoAuthenticationException for better error handling in SPNEGO authentication

Signed-off-by: raccoonback <[email protected]>

Author: raccoonback

reactor-netty-http/src/main/java/reactor/netty/http/client/SpnegoAuthProvider.java

@@ -107,7 +107,7 @@ public static SpnegoAuthProvider create(SpnegoAuthenticator authenticator, GSSMa
 	 * @param request the HTTP client request to authenticate
 	 * @param address the target server address (used for service principal)
 	 * @return a Mono that completes when the authentication is applied
-	 * @throws RuntimeException if login or token generation fails
+	 * @throws SpnegoAuthenticationException if login or token generation fails
 	 */
 	public Mono<Void> apply(HttpClientRequest request, InetSocketAddress address) {
 		if (verifiedAuthHeader != null) {
@@ -129,13 +129,13 @@ public Mono<Void> apply(HttpClientRequest request, InetSocketAddress address) {
 								return token;
 							}
 							catch (GSSException e) {
-								throw new RuntimeException("Failed to generate SPNEGO token", e);
+								throw new SpnegoAuthenticationException("Failed to generate SPNEGO token", e);
 							}
 						}
 					);
 				}
 				catch (LoginException e) {
-					throw new RuntimeException("Failed to login with SPNEGO", e);
+					throw new SpnegoAuthenticationException("Failed to login with SPNEGO", e);
 				}
 			})
 			.subscribeOn(boundedElastic())

reactor-netty-http/src/main/java/reactor/netty/http/client/SpnegoAuthenticationException.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2025 VMware, Inc. or its affiliates, All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package reactor.netty.http.client;
+
+/**
+ * Exception thrown when SPNEGO (Kerberos) authentication fails.
+ *
+ * @author raccoonback
+ * @since 1.3.0
+ */
+public class SpnegoAuthenticationException extends RuntimeException {
+
+	public SpnegoAuthenticationException(String message, Throwable cause) {
+		super(message, cause);
+	}
+}