nusoap exception Illegal argument invoking

the project made in laravel, call via SOAP to Web service in java, using nusoap complement

$factura=Facturas::find($id);
    $folio=$factura->folio.'L';
    $dataws=[
    'serie'=>$factura->serie,
    'folio'=>intval($folio),
    'rfcRecibido'=>$factura->distribuidor->rfc,
    'key'=>'xxxx-xxxx-xxx-xxxx-xxxx'
    ];
$websc = new nusoap_client('http://ift.tt/2bzMmkc');
    $error = $websc->getError();

when call function cancelCFD

$result = $websc->call('cancelaCFD', $dataws);
        if ($websc->fault) {
        echo '<h3>Error</h3><pre>';
        print_r($result);
        echo '</pre>';
            echo response()->json(array('success'=>false,'codigo'=>$result));
    }

the ws sends this

{"faultcode":"soap:Client","faultstring":"Illegal argument invoking 'com.tralix.xsa.manager.cancel.ws.ICancelService.cancelaCFD(java.lang.String, java.lang.Long, java.lang.String, java.lang.String)': java.lang.ClassCastException@40751341"}}

how make the integer value (folio) to long

via Chebli Mohamed