Javac compile error on cast to primitive when using generics wirldcards

FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
The following program does not compile using javac (but does compile using the eclipse compiler).

  public static void main(String... s) {
    List<?> l = Arrays.asList(1, 2, 3, 4);
    if (l.get(0) instanceof Integer) {
      System.out.println((int) l.get(0));
    }
  }

incompatible types: capture#1 of ? cannot be converted to int


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
  public static void main(String... s) {
    List<?> l = Arrays.asList(1, 2, 3, 4);
    if (l.get(0) instanceof Integer) {
      System.out.println((int) l.get(0));
    }
  }

-> incompatible types: capture#1 of ? cannot be converted to int
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
  public static void main(String... s) {
    List<?> l = Arrays.asList(1, 2, 3, 4);
    if (l.get(0) instanceof Integer) {
      System.out.println((Integer) l.get(0));
    }
  }

-> OK ! Just changing from primitive to object