VersionResourceResolver should delegate to the chain

Prior to this commit, the `VersionResourceResolver` implementation of
`resolveUrlPathInternal` would delegate to the resolver chain but would
never use the give result if the current request didn't match a
configured version strategy pattern.

This is a problem if the resolver supposed to resolve the resource path
is configured after a `VersionResourceResolver` in the resolver chain;
this means that other resolver never gets to participate in the result
of the chain.

Issue: SPR-15372
(cherry picked from commit fdd5031)

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -205,7 +205,7 @@ public class VersionResourceResolver extends AbstractResourceResolver {
 		if (StringUtils.hasText(baseUrl)) {
 			VersionStrategy versionStrategy = getStrategyForPath(resourceUrlPath);
 			if (versionStrategy == null) {
-				return null;
+				return baseUrl;
 			}
 			if (logger.isTraceEnabled()) {
 				logger.trace("Getting the original resource to determine version for path \"" + resourceUrlPath + "\"");

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -182,5 +182,12 @@ public class VersionResourceResolverTests {
 		assertThat(this.resolver.getStrategyForPath("fixedversion/css/something.css"), Matchers.instanceOf(FixedVersionStrategy.class));
 	}
 
+	@Test // SPR-15372
+	public void resolveUrlPathNoVersionStrategy() throws Exception {
+		given(this.chain.resolveUrlPath("/foo.css", this.locations)).willReturn("/foo.css");
+		String resolved = this.resolver.resolveUrlPathInternal("/foo.css", this.locations, this.chain);
+		assertThat(resolved, is("/foo.css"));
+	}
+
 
 }