Register prefixed path patterns with FixedVersionStrategy

Prior to this change, configuring a `FixedVersionStrategy` like so
would configure a single "/js/**" path pattern:

```
versionResourceResolver.addFixedVersionStrategy("v1.0.0","/js/**");
```

This commit makes sure that for each path pattern, its prefixed version
is added to the map. For example, the previous configuration also
adds "/v1.0.0/js/**".

Issue: SPR-13883
cherry-picked from 84fe46c

Author: bclozel

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java

@@ -22,6 +22,7 @@
 import java.net.URI;
 import java.net.URL;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.LinkedHashMap;
@@ -110,14 +111,26 @@ public VersionResourceResolver addContentVersionStrategy(String... pathPatterns)
 	 * fetched from a git commit sha, a property file, or environment variable
 	 * and set with SpEL expressions in the configuration (e.g. see {@code @Value}
 	 * in Java config).
+	 * <p>If not done already, variants of the given {@code pathPatterns}, prefixed with
+	 * the {@code version} will be also configured. For example, adding a {@code "/js/**"} path pattern
+	 * will also cofigure automatically a {@code "/v1.0.0/js/**"} with {@code "v1.0.0"} the
+	 * {@code version} String given as an argument.
 	 * @param version a version string
 	 * @param pathPatterns one or more resource URL path patterns
 	 * @return the current instance for chained method invocation
 	 * @see FixedVersionStrategy
 	 */
 	public VersionResourceResolver addFixedVersionStrategy(String version, String... pathPatterns) {
-		addVersionStrategy(new FixedVersionStrategy(version), pathPatterns);
-		return this;
+		List<String> patternsList = Arrays.asList(pathPatterns);
+		List<String> prefixedPatterns = new ArrayList<String>(pathPatterns.length);
+		String versionPrefix = "/" + version;
+		for(String pattern : patternsList) {
+			prefixedPatterns.add(pattern);
+			if(!pattern.startsWith(versionPrefix) && !patternsList.contains(versionPrefix + pattern)) {
+				prefixedPatterns.add(versionPrefix + pattern);
+			}
+		}
+		return addVersionStrategy(new FixedVersionStrategy(version), prefixedPatterns.toArray(new String[0]));
 	}
 
 	/**

spring-webmvc/src/test/java/org/springframework/web/servlet/resource/VersionResourceResolverTests.java

@@ -21,14 +21,15 @@
 import java.util.List;
 import java.util.Map;
 
+import org.hamcrest.Matchers;
 import org.junit.Before;
 import org.junit.Test;
 
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.mock.web.test.MockHttpServletRequest;
 
-import static org.hamcrest.Matchers.instanceOf;
+import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 import static org.mockito.BDDMockito.*;
 
@@ -168,4 +169,18 @@ public void getStrategyForPath() throws Exception {
 		assertEquals(jsStrategy, this.resolver.getStrategyForPath("bar/foo.js"));
 	}
 
+	// SPR-13883
+	@Test
+	public void shouldConfigureFixedPrefixAutomatically() throws Exception {
+
+		this.resolver.addFixedVersionStrategy("fixedversion", "/js/**", "/css/**", "/fixedversion/css/**");
+
+		assertThat(this.resolver.getStrategyMap().size(), is(4));
+		assertThat(this.resolver.getStrategyForPath("/js/something.js"), Matchers.instanceOf(FixedVersionStrategy.class));
+		assertThat(this.resolver.getStrategyForPath("/fixedversion/js/something.js"), Matchers.instanceOf(FixedVersionStrategy.class));
+		assertThat(this.resolver.getStrategyForPath("/css/something.css"), Matchers.instanceOf(FixedVersionStrategy.class));
+		assertThat(this.resolver.getStrategyForPath("/fixedversion/css/something.css"), Matchers.instanceOf(FixedVersionStrategy.class));
+	}
+
+
 }