COSDictionary trailer = doc.getTrailer();
// trailer.setLong(COSName.PREV, hybridPrev == -1 ? prev : hybridPrev);
trailer.setLong(COSName.PREV, doc.getStartXref());
pdfxRefStream.addTrailerInfo(trailer);
// the size is the highest object number+1. we add one more
// for the xref stream object we are going to write
pdfxRefStream.setSize(getNumber() + 2);
setStartxref(getStandardOutput().getPos());