Sync changes in MockHttpServletResponse test fixture

See gh-26558

spring-web/src/testFixtures/java/org/springframework/web/testfixture/servlet/MockHttpServletResponse.java

@@ -378,10 +378,10 @@ public class MockHttpServletResponse implements HttpServletResponse {
 			buf.append("; Domain=").append(cookie.getDomain());
 		}
 		int maxAge = cookie.getMaxAge();
+		ZonedDateTime expires = (cookie instanceof MockCookie ? ((MockCookie) cookie).getExpires() : null);
 		if (maxAge >= 0) {
 			buf.append("; Max-Age=").append(maxAge);
 			buf.append("; Expires=");
-			ZonedDateTime expires = (cookie instanceof MockCookie ? ((MockCookie) cookie).getExpires() : null);
 			if (expires != null) {
 				buf.append(expires.format(DateTimeFormatter.RFC_1123_DATE_TIME));
 			}
@@ -391,6 +391,10 @@ public class MockHttpServletResponse implements HttpServletResponse {
 				buf.append(headers.getFirst(HttpHeaders.EXPIRES));
 			}
 		}
+		else if (expires != null) {
+			buf.append("; Expires=");
+			buf.append(expires.format(DateTimeFormatter.RFC_1123_DATE_TIME));
+		}
 
 		if (cookie.getSecure()) {
 			buf.append("; Secure");