Add sample for OAuth2 RestClient interceptor

Closes gh-294

servlet/spring-boot/java/oauth2/resource-server/restclient/src/main/java/example/MessagesController.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2002-2024 the original author or authors.
+ *
+ * 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 example;
+
+import java.util.List;
+
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+/**
+ * Messages controller.
+ *
+ * @author Steve Riesenberg
+ */
+@RestController
+public class MessagesController {
+
+	@GetMapping("/messages")
+	public List<Message> messages() {
+		return List.of(new Message("Hello"), new Message("Goodbye"));
+	}
+
+	public record Message(String message) {
+	}
+
+}

servlet/spring-boot/java/oauth2/resource-server/restclient/src/main/java/example/OAuth2ResourceServerApplication.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2002-2024 the original author or authors.
+ *
+ * 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 example;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+/**
+ * OAuth2 Resource Server application.
+ *
+ * @author Steve Riesenberg
+ */
+@SpringBootApplication
+public class OAuth2ResourceServerApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(OAuth2ResourceServerApplication.class, args);
+	}
+
+}

servlet/spring-boot/java/oauth2/resource-server/restclient/src/main/java/example/SecurityConfiguration.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2002-2024 the original author or authors.
+ *
+ * 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 example;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.http.HttpMethod;
+import org.springframework.security.config.Customizer;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
+import org.springframework.security.web.SecurityFilterChain;
+
+/**
+ * Security configuration for {@link OAuth2ResourceServerApplication}.
+ *
+ * @author Steve Riesenberg
+ */
+@Configuration
+@EnableWebSecurity
+public class SecurityConfiguration {
+
+	@Bean
+	public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
+		// @formatter:off
+		http
+			.authorizeHttpRequests((authorize) -> authorize
+				.requestMatchers(HttpMethod.GET, "/messages/**").hasAuthority("SCOPE_message:read")
+				.requestMatchers(HttpMethod.POST, "/messages/**").hasAuthority("SCOPE_message:write")
+				.anyRequest().denyAll()
+			)
+			.oauth2ResourceServer((oauth2) -> oauth2
+				.jwt(Customizer.withDefaults())
+			);
+		// @formatter:on
+		return http.build();
+	}
+
+}

servlet/spring-boot/java/oauth2/resource-server/restclient/src/main/resources/application.yml

@@ -0,0 +1,13 @@
+server:
+  port: 8090
+
+logging:
+  level:
+    org.springframework.security: trace
+
+spring:
+  security:
+    oauth2:
+      resourceserver:
+        jwt:
+          jwk-set-uri: http://localhost:9000/oauth2/jwks