java.lang.Integer and the other wrapper classes contain code like

    @SuppressWarnings("unchecked")
    public static final Class<Integer>  TYPE = (Class<Integer>) Class.getPrimitiveClass("int");

where Class.getPrimitiveClass is a package-private static method returning a Class<?>.

Despite the @SuppressWarnings annotation, javac still reports an unchecked warning on this code:

src/share/classes/java/lang/Integer.java:72: warning: [unchecked] unchecked cast
    public static final Class<Integer>  TYPE = (Class<Integer>) Class.getPrimitiveClass("int");
                                                                                       ^
  required: Class<Integer>
  found:    Class<CAP#1>
  where CAP#1 is a fresh type-variable:
    CAP#1 extends Object from capture of ?

This behavior is unfortunate since it frustrates efforts to resolve lint warnings in the JDK.