Find exact matches in WebJarsResourceResolver

Prior to this commit, resolving resources from webjars using the
`WebJarAssetLocator.getFullPath` could lead to multiple candidates,
since this method is trying to find *any* resource matching that path
under the given webjar location.

This commit replaces that call with
`WebJarAssetLocator.getFullPathExact`, which avoids those multiple
matches and only resolves resources if the given path is exact.

Issue: SPR-15526
(cherry picked from commit e2aa117)

Author: Skarafaz

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/WebJarsResourceResolver.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.
@@ -17,9 +17,9 @@
 package org.springframework.web.servlet.resource;
 
 import java.util.List;
+
 import javax.servlet.http.HttpServletRequest;
 
-import org.webjars.MultipleMatchesException;
 import org.webjars.WebJarAssetLocator;
 
 import org.springframework.core.io.Resource;
@@ -99,26 +99,16 @@ protected String resolveUrlPathInternal(String resourceUrlPath,
 	}
 
 	protected String findWebJarResourcePath(String path) {
-		try {
-			int startOffset = (path.startsWith("/") ? 1 : 0);
-			int endOffset = path.indexOf("/", 1);
-			if (endOffset != -1) {
-				String webjar = path.substring(startOffset, endOffset);
-				String partialPath = path.substring(endOffset);
-				String webJarPath = webJarAssetLocator.getFullPath(webjar, partialPath);
+		int startOffset = (path.startsWith("/") ? 1 : 0);
+		int endOffset = path.indexOf("/", 1);
+		if (endOffset != -1) {
+			String webjar = path.substring(startOffset, endOffset);
+			String partialPath = path.substring(endOffset + 1);
+			String webJarPath = webJarAssetLocator.getFullPathExact(webjar, partialPath);
+			if (webJarPath != null) {
 				return webJarPath.substring(WEBJARS_LOCATION_LENGTH);
 			}
 		}
-		catch (MultipleMatchesException ex) {
-			if (logger.isWarnEnabled()) {
-				logger.warn("WebJar version conflict for \"" + path + "\"", ex);
-			}
-		}
-		catch (IllegalArgumentException ex) {
-			if (logger.isTraceEnabled()) {
-				logger.trace("No WebJar resource found for \"" + path + "\"");
-			}
-		}
 		return null;
 	}