code: @ReplacedBy("com.google.common.primitives.Ints#toArray()")
      public static int[] toIntArray (Collection<Integer> col)
      {
          Iterator<Integer> iter = col.iterator();
          int[] array = new int[col.size()];
          for (int i = 0; iter.hasNext(); i++) {
              array[i] = iter.next().intValue();
          }
          return array;
      }
docs: If a collection contains only <code>Integer</code> objects, it can be
  passed to this function and converted into an int array.
  
  @param col the collection to be converted.
  
  @return an int array containing the contents of the collection (in the
  order returned by the collection's iterator). The size of the array will
  be equal to the size of the collection.