How to get collapsed columns in Table?

Hello!, One question, how to get  collapsed columns in table?
Now i get all table colums:

String[] tableHeaders = table.getColumnHeaders();
Row row = sheet.createRow(0);
for(int i=0;i<tableHeaders.length;i++){
  String headerItem = tableHeaders[i];
  System.out.print("\n"+headerItem);
  Cell cell = row.createCell(i);
  cell.setCellType(CellType.STRING);
  cell.setCellValue(headerItem);
  cell.setCellStyle(style);
  sheet.autoSizeColumn(i);
}

But i need get all active colums, with out collapsed