diff --git a/spring-web/src/main/java/org/springframework/http/CacheControl.java b/spring-web/src/main/java/org/springframework/http/CacheControl.java
index a78ed947d54..a7b29acda41 100644
--- a/spring-web/src/main/java/org/springframework/http/CacheControl.java
+++ b/spring-web/src/main/java/org/springframework/http/CacheControl.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -326,6 +326,8 @@ public class CacheControl {
 	 * Add an "immutable" directive.
 	 * <p>This directive indicates that the origin server will not update the
 	 * representation of that resource during the freshness lifetime of the response.
+	 * Adding a {@link #maxAge(Duration) max-age} directive is strongly advised
+	 * to enforce the actual freshness lifetime.
 	 * @return {@code this}, to facilitate method chaining
 	 * @see <a href="https://tools.ietf.org/html/rfc8246">rfc8246</a>
 	 */
diff --git a/spring-web/src/test/java/org/springframework/http/CacheControlTests.java b/spring-web/src/test/java/org/springframework/http/CacheControlTests.java
index 8dfdf91406c..c0066c4fd77 100644
--- a/spring-web/src/test/java/org/springframework/http/CacheControlTests.java
+++ b/spring-web/src/test/java/org/springframework/http/CacheControlTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -25,84 +25,85 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 
 /**
+ * Tests for {@link CacheControl}.
  * @author Brian Clozel
  */
-public class CacheControlTests {
+class CacheControlTests {
 
 	@Test
-	public void emptyCacheControl() throws Exception {
+	void emptyCacheControl() {
 		CacheControl cc = CacheControl.empty();
 		assertThat(cc.getHeaderValue()).isNull();
 	}
 
 	@Test
-	public void maxAge() throws Exception {
+	void maxAge() {
 		CacheControl cc = CacheControl.maxAge(1, TimeUnit.HOURS);
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600");
 	}
 
 	@Test
-	public void maxAge_duration() throws Exception {
+	void maxAge_duration() {
 		CacheControl cc = CacheControl.maxAge(Duration.ofHours(1));
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600");
 	}
 
 	@Test
-	public void maxAgeAndDirectives() throws Exception {
+	void maxAgeAndDirectives() {
 		CacheControl cc = CacheControl.maxAge(3600, TimeUnit.SECONDS).cachePublic().noTransform();
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600, no-transform, public");
 	}
 
 	@Test
-	public void maxAgeAndSMaxAge() throws Exception {
+	void maxAgeAndSMaxAge() {
 		CacheControl cc = CacheControl.maxAge(1, TimeUnit.HOURS).sMaxAge(30, TimeUnit.MINUTES);
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600, s-maxage=1800");
 	}
 
 	@Test
-	public void maxAgeAndSMaxAge_duration() throws Exception {
+	void maxAgeAndSMaxAge_duration() {
 		CacheControl cc = CacheControl.maxAge(Duration.ofHours(1)).sMaxAge(Duration.ofMinutes(30));
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600, s-maxage=1800");
 	}
 
 	@Test
-	public void noCachePrivate() throws Exception {
+	void noCachePrivate() {
 		CacheControl cc = CacheControl.noCache().cachePrivate();
 		assertThat(cc.getHeaderValue()).isEqualTo("no-cache, private");
 	}
 
 	@Test
-	public void noStore() throws Exception {
+	void noStore() {
 		CacheControl cc = CacheControl.noStore();
 		assertThat(cc.getHeaderValue()).isEqualTo("no-store");
 	}
 
 	@Test
-	public void staleIfError() throws Exception {
+	void staleIfError() {
 		CacheControl cc = CacheControl.maxAge(1, TimeUnit.HOURS).staleIfError(2, TimeUnit.HOURS);
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600, stale-if-error=7200");
 	}
 
 	@Test
-	public void staleIfError_duration() throws Exception {
+	void staleIfError_duration() {
 		CacheControl cc = CacheControl.maxAge(Duration.ofHours(1)).staleIfError(2, TimeUnit.HOURS);
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600, stale-if-error=7200");
 	}
 
 	@Test
-	public void staleWhileRevalidate() throws Exception {
+	void staleWhileRevalidate() {
 		CacheControl cc = CacheControl.maxAge(1, TimeUnit.HOURS).staleWhileRevalidate(2, TimeUnit.HOURS);
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600, stale-while-revalidate=7200");
 	}
 
 	@Test
-	public void staleWhileRevalidate_duration() throws Exception {
+	void staleWhileRevalidate_duration() {
 		CacheControl cc = CacheControl.maxAge(Duration.ofHours(1)).staleWhileRevalidate(2, TimeUnit.HOURS);
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600, stale-while-revalidate=7200");
 	}
 
 	@Test
-	public void immutable() throws Exception {
+	void immutable() {
 		CacheControl cc = CacheControl.maxAge(Duration.ofHours(1)).immutable();
 		assertThat(cc.getHeaderValue()).isEqualTo("max-age=3600, immutable");
 	}