code: public static PdfObject getXfaObject(PdfReader reader) {
      	PdfDictionary af = (PdfDictionary)PdfReader.getPdfObjectRelease(reader.getCatalog().get(PdfName.ACROFORM));
          if (af == null) {
              return null;
          }
          return PdfReader.getPdfObjectRelease(af.get(PdfName.XFA));
      }
docs: Return the XFA Object, could be an array, could be a Stream.
  Returns null f no XFA Object is present.
  @param	reader	a PdfReader instance
  @return	the XFA object
  @since	2.1.3