javac does not issue unchecked warnings when checking method reference return types

Initially seen here:
http://stackoverflow.com/questions/42346895/constructor-reference-no-warning-when-generics-array-is-created

Javac does not generate unchecked warnings when checking method reference return types. The issue is not limited to arrays.

import java.util.function.*;
import java.util.*;

class Test {
   void m() {
            IntFunction<List<String>[]> sls = List[]::new; //no warning
      Supplier<List<String>> sls = this::l; //no warning
   }

   List l() { return null; }
}