diff --git a/spring-webflux/src/main/java/org/springframework/web/reactive/resource/AppCacheManifestTransformer.java b/spring-webflux/src/main/java/org/springframework/web/reactive/resource/AppCacheManifestTransformer.java
index 58ea4ab7fc..e6d2d56a58 100644
--- a/spring-webflux/src/main/java/org/springframework/web/reactive/resource/AppCacheManifestTransformer.java
+++ b/spring-webflux/src/main/java/org/springframework/web/reactive/resource/AppCacheManifestTransformer.java
@@ -68,13 +68,13 @@ import org.springframework.web.server.ServerWebExchange;
  */
 public class AppCacheManifestTransformer extends ResourceTransformerSupport {
 
-	private static final Collection<String> MANIFEST_SECTION_HEADERS =
-			Arrays.asList("CACHE MANIFEST", "NETWORK:", "FALLBACK:", "CACHE:");
-
 	private static final String MANIFEST_HEADER = "CACHE MANIFEST";
 
 	private static final String CACHE_HEADER = "CACHE:";
 
+	private static final Collection<String> MANIFEST_SECTION_HEADERS =
+			Arrays.asList(MANIFEST_HEADER, "NETWORK:", "FALLBACK:", CACHE_HEADER);
+
 	private static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
 
 	private static final Log logger = LogFactory.getLog(AppCacheManifestTransformer.class);
@@ -212,8 +212,9 @@ public class AppCacheManifestTransformer extends ResourceTransformerSupport {
 
 
 		private static boolean initCacheSectionFlag(String line, @Nullable LineInfo previousLine) {
-			if (MANIFEST_SECTION_HEADERS.contains(line.trim())) {
-				return line.trim().equals(CACHE_HEADER);
+			String trimmedLine = line.trim();
+			if (MANIFEST_SECTION_HEADERS.contains(trimmedLine)) {
+				return trimmedLine.equals(CACHE_HEADER);
 			}
 			else if (previousLine != null) {
 				return previousLine.isCacheSection();
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/AppCacheManifestTransformer.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/AppCacheManifestTransformer.java
index 8868b5c54f..fb3bdd0b30 100644
--- a/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/AppCacheManifestTransformer.java
+++ b/spring-webmvc/src/main/java/org/springframework/web/servlet/resource/AppCacheManifestTransformer.java
@@ -65,13 +65,13 @@ import org.springframework.util.StringUtils;
  */
 public class AppCacheManifestTransformer extends ResourceTransformerSupport {
 
-	private static final Collection<String> MANIFEST_SECTION_HEADERS =
-			Arrays.asList("CACHE MANIFEST", "NETWORK:", "FALLBACK:", "CACHE:");
-
 	private static final String MANIFEST_HEADER = "CACHE MANIFEST";
 
 	private static final String CACHE_HEADER = "CACHE:";
 
+	private static final Collection<String> MANIFEST_SECTION_HEADERS =
+			Arrays.asList(MANIFEST_HEADER, "NETWORK:", "FALLBACK:", CACHE_HEADER);
+
 	private static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
 
 	private static final Log logger = LogFactory.getLog(AppCacheManifestTransformer.class);
@@ -168,8 +168,9 @@ public class AppCacheManifestTransformer extends ResourceTransformerSupport {
 		}
 
 		private static boolean initCacheSectionFlag(String line, @Nullable LineInfo previousLine) {
-			if (MANIFEST_SECTION_HEADERS.contains(line.trim())) {
-				return line.trim().equals(CACHE_HEADER);
+			String trimmedLine = line.trim();
+			if (MANIFEST_SECTION_HEADERS.contains(trimmedLine)) {
+				return trimmedLine.equals(CACHE_HEADER);
 			}
 			else if (previousLine != null) {
 				return previousLine.isCacheSection();