code: private final void advanceToNonNullItem() {
          assert _iterator != null;
          assert _currentItem == null;
  
          while(_iterator.hasNext() && _currentItem == null) {
              _currentItem = _iterator.next();
              _currentIndex++;
          }
      }
docs: <p/>
  Internal utility method.
  </p>
  </p>
  This is called in places where the repeater needs to move to the next
  non-null item in the data set to render.  This occurs when the
  current data item is null and the <code>ignoreNulls</code>
  flag has been set to skip rendering null items in the data set.
  </p>
  <p/>
  This method side-effects to advance the iterator to the next
  non-null item or the end if there are zero remaining non-null
  items.
  </p>
  <p/>
  At the end, the <code>currentItem</code> may be null, and the
  <code>currentIndex</code> will reference either the integer
  location in the data structure of the non-null data item, or
  it will reference the end of the data structure.
  </p>