Revert ParsingPathMatcher concurrency checks

`PathPatternParser` is now thread-safe and creates a new internal parser
for each `parse` call, since this operation is cheap.
This commit removes the `ThreadLocal` based instances of
`PathPatternParser` in `ParsingPathMatcher` which are not required
anymore.

Issue: SPR-15246

Author: bclozel

spring-web/src/main/java/org/springframework/web/util/ParsingPathMatcher.java

@@ -43,8 +43,7 @@ public class ParsingPathMatcher implements PathMatcher {
 	private final ConcurrentMap<String, PathPattern> cache =
 			new ConcurrentHashMap<>(64);
 
-	private static final ThreadLocal<PathPatternParser> PARSER
-			= ThreadLocal.withInitial(() -> new PathPatternParser());
+	private final PathPatternParser parser = new PathPatternParser();
 
 	@Override
 	public boolean match(String pattern, String path) {
@@ -113,7 +112,7 @@ public boolean isPattern(String path) {
 	private PathPattern getPathPattern(String pattern) {
 		PathPattern pathPattern = this.cache.get(pattern);
 		if (pathPattern == null) {
-			pathPattern = PARSER.get().parse(pattern);
+			pathPattern = this.parser.parse(pattern);
 			this.cache.put(pattern, pathPattern);
 		}
 		return pathPattern;

spring-web/src/main/java/org/springframework/web/util/patterns/PathPatternParser.java

@@ -63,9 +63,9 @@ public void setCaseSensitive(boolean caseSensitive) {
 	 * @param pathPattern the input path pattern, e.g. /foo/{bar}
 	 * @return a PathPattern for quickly matching paths against the specified path pattern
 	 */
-	public PathPattern parse(String pattern) {
+	public PathPattern parse(String pathPattern) {
 		InternalPathPatternParser ippp = new InternalPathPatternParser(separator, caseSensitive);
-		return ippp.parse(pattern);
+		return ippp.parse(pathPattern);
 	}
 
 }