Do not rewrite relative links with FixedVersionStrategy

Prior to this change, the resource handling FixedVersionStrategy would
be applied on all links that match the configured pattern. This is
problematic for relative links and can lead to rewritten links such as
"/fixedversion/../css/main.css" which breaks.

This commit prevents that Strategy from being applied to such links.
Of course, one should avoid to use that VersionStrategy with relative
links, but this change aims at not breaking existing links even if it
means not prefixing the version as expected.

Issue: SPR-13727

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

@@ -100,7 +100,12 @@ public abstract class AbstractVersionStrategy implements VersionStrategy {
 
 		@Override
 		public String addVersion(String path, String version) {
-			return (this.prefix.endsWith("/") || path.startsWith("/") ? this.prefix + path : this.prefix + "/" + path);
+			if(path.startsWith(".")) {
+				return path;
+			}
+			else {
+				return (this.prefix.endsWith("/") || path.startsWith("/") ? this.prefix + path : this.prefix + "/" + path);
+			}
 		}
 	}
 

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

@@ -57,7 +57,14 @@ public class FixedVersionStrategyTests {
 
 	@Test
 	public void addVersion() throws Exception {
-		assertEquals(this.version + "/" + this.path, this.strategy.addVersion(this.path, this.version));
+		assertEquals(this.version + "/" + this.path, this.strategy.addVersion("/" + this.path, this.version));
+	}
+
+	// SPR-13727
+	@Test
+	public void addVersionRelativePath() throws Exception {
+		String relativePath = "../" + this.path;
+		assertEquals(relativePath, this.strategy.addVersion(relativePath, this.version));
 	}
 
 }