diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctions.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctions.java
index 5fa6a64774..92943358d3 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctions.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/RouterFunctions.java
@@ -143,10 +143,10 @@ public abstract class RouterFunctions {
 	 * The returned function can be {@linkplain Function#andThen(Function) composed} on, for
 	 * instance to return a default resource when the lookup function does not match:
 	 * <pre class="code">
-	 * Mono&lt;Resource&gt; defaultResource = Mono.just(new ClassPathResource("index.html"));
-	 * Function&lt;ServerRequest, Mono&lt;Resource&gt;&gt; lookupFunction =
+	 * Optional&lt;Resource&gt; defaultResource = Optional.of(new ClassPathResource("index.html"));
+	 * Function&lt;ServerRequest, Optional&lt;Resource&gt;&gt; lookupFunction =
 	 *   RouterFunctions.resourceLookupFunction("/resources/**", new FileSystemResource("public-resources/"))
-	 *     .andThen(resourceMono -&gt; resourceMono.switchIfEmpty(defaultResource));
+	 *     .andThen(resource -&gt; resource.or(() -&gt; defaultResource));
 	 * RouterFunction&lt;ServerResponse&gt; resources = RouterFunctions.resources(lookupFunction);
      * </pre>
 	 * @param pattern the pattern to match
@@ -168,11 +168,6 @@ public abstract class RouterFunctions {
 		return new ResourcesRouterFunction(lookupFunction);
 	}
 
-	@SuppressWarnings("unchecked")
-	static <T extends ServerResponse> HandlerFunction<T> cast(HandlerFunction<?> handlerFunction) {
-		return (HandlerFunction<T>) handlerFunction;
-	}
-
 
 	/**
 	 * Represents a discoverable builder for router functions.
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/ServerResponse.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/ServerResponse.java
index 1a591c37b1..89b476ec08 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/ServerResponse.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/ServerResponse.java
@@ -76,7 +76,7 @@ public interface ServerResponse {
 	 * @param request the current request
 	 * @param response the response to write to
 	 * @param context the context to use when writing
-	 * @return {@code Mono<Void>} to indicate when writing is complete
+	 * @return a ModelAndView to render, or {@code null} if handled directly
 	 */
 	@Nullable
 	ModelAndView writeTo(HttpServletRequest request, HttpServletResponse response, Context context)