I am using laravel koolreport My Datatables setting is

  DataTables::create([
            "dataSource"=>$finaloutput,
            "complexHeaders" => true,
            "headerSeparator" => "-",
            "options"=>array(
                "paging"=>true,
                "pageLength" => 10,
                "searching"=>true,
                "colReorder"=>true,
                "order"=>array(
                    array(0,"desc"), //Sort by first column desc
                ),
            ),
            "searchOnEnter" => true,
            "searchMode" => "or",
            "themeBase"=>"bs4",
            "columns"=>array(
                "year_of_complain"=>array(
                    "label"=>"YEAR",
                   // "type"=>"number",
                    "searchable" => true,
                    "type"=>"datetime",
                    "format"=>"Y-m-d H:i:s",
                    "displayFormat"=>"Y"
                ),
                "total"=>array(
                  "label"=>"TOTAL COMPLAINTS",
                  "type"=>"number",
                  //"searchable" => true,
                ),
                "total1"=>array(
                    "label"=>"CLOSED",
                    "type"=>"number",
                    //"searchable" => true,
                ),
                "total2"=>array(
                    "label"=>"ON-GOING",
                    "type"=>"number",
                    //"searchable" => true,
                  )
            ),
            "cssClass"=>array(
                "table"=>"table table-striped table-bordered"
            )
        ]);

I want to show one complex header top of 3 total value. Please help me