code: public static int[] unbox (Integer[] list)
      {
          if (list == null) {
              return null;
          }
          int[] unboxed = new int[list.length];
          for (int ii = 0; ii < list.length; ii++) {
              unboxed[ii] = list[ii];
          }
          return unboxed;
      }
docs: Converts an array of Integer objects to an array of primitives.