code: protected PdfDictionary getCatalog(PdfIndirectReference rootObj) {
          try {
              PdfDictionary theCat = pdf.getCatalog(rootObj);
              if (fieldArray == null) {
                  if (acroForm != null) theCat.put(PdfName.ACROFORM, acroForm);
              }
              else
                  addFieldResources(theCat);
              return theCat;
          }
          catch (IOException e) {
              throw new ExceptionConverter(e);
          }
      }
docs: /*
  the getCatalog method is part of PdfWriter.
  we wrap this so that we can extend it