Add getAttribute to WebSession and ServerWebExchange

spring-web-reactive/src/main/java/org/springframework/web/server/ServerWebExchange.java

@@ -16,6 +16,7 @@
 package org.springframework.web.server;
 
 import java.util.Map;
+import java.util.Optional;
 
 import reactor.core.publisher.Mono;
 
@@ -46,6 +47,14 @@ public interface ServerWebExchange {
 	 */
 	Map<String, Object> getAttributes();
 
+	/**
+	 * Return the request attribute value if present.
+	 * @param name the attribute name
+	 * @param <T> the attribute type
+	 * @return the attribute value
+	 */
+	<T> Optional<T> getAttribute(String name);
+
 	/**
 	 * Return the web session for the current request. Always guaranteed  to
 	 * return an instance either matching to the session id requested by the

spring-web-reactive/src/main/java/org/springframework/web/server/WebSession.java

@@ -18,6 +18,7 @@ package org.springframework.web.server;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Map;
+import java.util.Optional;
 
 import reactor.core.publisher.Mono;
 
@@ -44,6 +45,14 @@ public interface WebSession {
 	 */
 	Map<String, Object> getAttributes();
 
+	/**
+	 * Return the attribute value if present.
+	 * @param name the attribute name
+	 * @param <T> the attribute type
+	 * @return the attribute value
+	 */
+	<T> Optional<T> getAttribute(String name);
+
 	/**
 	 * Force the creation of a session causing the session id to be sent when
 	 * {@link #save()} is called.

spring-web-reactive/src/main/java/org/springframework/web/server/adapter/DefaultServerWebExchange.java

@@ -16,6 +16,7 @@
 package org.springframework.web.server.adapter;
 
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 
 import reactor.core.publisher.EmitterProcessor;
@@ -78,6 +79,11 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 		return this.attributes;
 	}
 
+	@Override @SuppressWarnings("unchecked")
+	public <T> Optional<T> getAttribute(String name) {
+		return Optional.ofNullable((T) this.attributes.get(name));
+	}
+
 	@Override
 	public Mono<WebSession> getSession() {
 		if (this.sessionMono == null) {

spring-web-reactive/src/main/java/org/springframework/web/server/session/DefaultWebSession.java

@@ -20,6 +20,7 @@ import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Supplier;
@@ -101,6 +102,11 @@ public class DefaultWebSession implements ConfigurableWebSession, Serializable {
 		return this.attributes;
 	}
 
+	@Override @SuppressWarnings("unchecked")
+	public <T> Optional<T> getAttribute(String name) {
+		return Optional.ofNullable((T) this.attributes.get(name));
+	}
+
 	@Override
 	public Instant getCreationTime() {
 		return this.creationTime;