Avoid use of deprecated Character/Double constructors in tests

spring-web/src/test/java/org/springframework/web/context/request/ServletRequestAttributesTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -153,7 +153,7 @@ public class ServletRequestAttributesTests {
 
 	@Test
 	public void skipImmutableCharacter() {
-		doSkipImmutableValue(new Character('x'));
+		doSkipImmutableValue('x');
 	}
 
 	@Test