Support "*" mapping in MockMvc filter registration

Prior to this commit, configuring a Servlet filter in MockMvc with a
defined mapping would only consider "/*" as a catch-all pattern.

This commit relaxes this rule by also accepting "*" mappings.

Closes gh-28041

spring-test/src/main/java/org/springframework/test/web/servlet/setup/MockMvcFilterDecorator.java

@@ -47,9 +47,11 @@ import org.springframework.web.util.UrlPathHelper;
  */
 final class MockMvcFilterDecorator implements Filter {
 
-	private static final String EXTENSION_MAPPING_PATTERN = "*.";
+	private static final String ALL_MAPPING_PATTERN = "*";
 
-	private static final String PATH_MAPPING_PATTERN = "/*";
+	private static final String EXTENSION_MAPPING_PATTERN = ALL_MAPPING_PATTERN + ".";
+
+	private static final String PATH_MAPPING_PATTERN = "/" + ALL_MAPPING_PATTERN;
 
 	private final Filter delegate;
 
@@ -103,7 +105,7 @@ final class MockMvcFilterDecorator implements Filter {
 		if (urlPattern.startsWith(EXTENSION_MAPPING_PATTERN)) {
 			this.endsWithMatches.add(urlPattern.substring(1));
 		}
-		else if (urlPattern.equals(PATH_MAPPING_PATTERN)) {
+		else if (urlPattern.equals(PATH_MAPPING_PATTERN) || urlPattern.equals(ALL_MAPPING_PATTERN)) {
 			this.startsWithMatches.add("");
 		}
 		else if (urlPattern.endsWith(PATH_MAPPING_PATTERN)) {

spring-test/src/test/java/org/springframework/test/web/servlet/setup/MockMvcFilterDecoratorTests.java

@@ -95,7 +95,7 @@ public class MockMvcFilterDecoratorTests {
 
 	@Test
 	public void matchPathMappingAll() throws Exception {
-		assertFilterInvoked("/test", "/*");
+		assertFilterInvoked("/test", "*");
 	}
 
 	@Test