This program should continue to not compile:

import java.util.*;

class Test {

     private static <T> T method(Collection<? super T> arg) {
              return null;
     }

     private static void test5(Collection<?> arg) {
         Class<? extends String> c = method(arg).getClass();
     }
}
This program does not compile:

import java.util.*;

class Test {

     private static <T> T method(Collection<? super T> arg) {
              return null;
     }

     private static void test4(Collection<? super String> arg) {
         Class<? extends String> c = method(arg).getClass();
     }
     private static void test6(Collection<String> arg) {
         Class<? extends String> c = method(arg).getClass();
     }
}