The following error occured
  ---------------------------
  Exception in thread main
  java.lang.NullPointerException
        at org.apache.poi.hssf.model.Sheet.getNumColumnBreaks(Sheet.java:2721)
  ---------------------------

in the following code

  ---------------------------
  import java.io.FileInputStream;
  import java.io.IOException;

  import org.apache.poi.hssf.usermodel.HSSFSheet;
  import org.apache.poi.hssf.usermodel.HSSFWorkbook;
  import org.apache.poi.poifs.filesystem.POIFSFileSystem;

  public class GridSetError  {
    public GridSetError( String fileName ) {

      System.out.println( "fileName : " + fileName );
      try {
        POIFSFileSystem pfs = new POIFSFileSystem( new FileInputStream( fileName
) );
        HSSFWorkbook sourceWorkbook = new HSSFWorkbook( pfs );
        HSSFSheet sourceSheet = sourceWorkbook.getSheetAt( 0 );
        System.out.println( sourceSheet.getColumnBreaks() );
      }
      catch( IOException ioE ) {}
    }

    public static void main(String[] args) {
      if( args.length > 0 ) {
        GridSetError gridSetError = new GridSetError( args[0] );
      }
    }
  }
  ---------------------------

Source XLS DOES NOT contain [VERTICALPAGEBREAK] record.

I think, Sheet.getNumColumnBreaks() ( and Sheet.getNumRowBreaks() ) should first
test if Sheet.colBreaks (and Sheet.rowBreaks) is not null and if it is, then
return 0 to HSSFSheet.getColumnBreaks() which would then return empty short[] to
the caller. This would not result in exception.