Why is CellIdentifier set on struct not seen after return? Am I passing my value?

gistfile1.go

type LayoutCell struct
{
  CellIdentifier string;
  CellWidth int;

  Widget_name string;
  Widget_state *interface{};
}

type LayoutRow struct // CellGroup
{
  Cells *[]LayoutCell;
}

type Document []LayoutRow;

func LoadDocument(filename string) (*Document, error) {
  // Read file from disc
  doc_bytes, err := ioutil.ReadFile(filename);
  if (err != nil) { return nil, err; }

  var document = make(Document, 0);

  var parse_err = json.Unmarshal(doc_bytes, &document);
  if (parse_err != nil) { return nil, parse_err; }

  // Set CellIdentifiers
  for _, layoutRow := range document { // Rows loop

    // Loop on cells in range
    for i, cell := range *layoutRow.Cells { // Cells loop
   
      cell.CellIdentifier = "cell-" + strconv.Itoa(i);
      log.Print(cell.CellIdentifier); // Set cell identifier here! Why is this not seen on document?
    }
    
  }


  return &document, nil;
}

func main() {
  var document = LoadDocument("mytest.json");
  
  // Why is cell.CellIdentifier empty here?
  for _, layoutRow := range document { // Rows loop
    // Loop on cells in range
    for i, cell := range *layoutRow.Cells { // Cells loop
   
      log.Print(cell.CellIdentifier); // Outputs empty string!
    }
  }
  
}