Polish 0cfbf60: fix a test for Java 8 compatibility

Author: simonbasle

spring-test/src/test/java/org/springframework/test/web/client/match/MockRestRequestMatchersTests.java

@@ -212,7 +212,7 @@ void headerListContainsMismatch() {
 
 	@Test
 	void headerListDoesntHideHeaderWithSingleMatcher() throws IOException {
-		this.request.getHeaders().put("foo", List.of("bar", "baz"));
+		this.request.getHeaders().put("foo", Arrays.asList("bar", "baz"));
 
 		MockRestRequestMatchers.header("foo", equalTo("bar")).match(this.request);