code: void setTransition(PdfTransition transition, int page) {
          PdfDictionary pg = reader.getPageN(page);
          if (transition == null)
              pg.remove(PdfName.TRANS);
          else
              pg.put(PdfName.TRANS, transition.getTransitionDictionary());
          markUsed(pg);
      }
docs: Sets the transition for the page
  @param transition   the transition object. A <code>null</code> removes the transition
  @param page the page where the transition will be applied. The first page is 1