Consistent use of Collection.toArray with zero-sized array argument

Includes consistent use of ClassUtils.toClassArray (as non-null variant)

Issue: SPR-16523

spring-web/src/test/java/org/springframework/mock/web/test/MockHttpServletResponse.java

@@ -349,7 +349,7 @@ public class MockHttpServletResponse implements HttpServletResponse {
 	}
 
 	public Cookie[] getCookies() {
-		return this.cookies.toArray(new Cookie[this.cookies.size()]);
+		return this.cookies.toArray(new Cookie[0]);
 	}
 
 	public Cookie getCookie(String name) {