getRealPath return nullpointer create PDF jsf using itex

//create a new file pdf from a model existing in workspace

String MODEL = FacesContext.getCurrentInstance().getExternalContext().getRealPath("//resources//pdf//"+etd.getEtablissement()+".pdf"); System.out.println("Test Test"+MODEL);

  String RESULT=FacesContext.getCurrentInstance().getExternalContext().getRealPath("//resources//pdf//"+Util.getCne()+".pdf");


  System.out.println("Test Test"+RESULT);   //return null
    PdfReader reader = new PdfReader(MODEL);


    PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(RESULT));
    PdfContentByte canvas = stamper.getOverContent(1);