Final Class Yiisoft\Yii\DataView\GridView\Column\CheckboxColumnRenderer

                public function renderBody(ColumnInterface $column, Cell $cell, DataContext $context): Cell
{
    $inputAttributes = $column->inputAttributes;
    $name = null;
    $value = null;
    if (!array_key_exists('name', $inputAttributes)) {
        $name = 'checkbox-selection';
    }
    if (!array_key_exists('value', $inputAttributes)) {
        $value = $context->key;
    }
    $input = Html::checkbox($name, $value, $inputAttributes);
    $content = $column->content === null
        ? $input
        : ($column->content)($input, $context);
    return $cell
        ->addAttributes($column->bodyAttributes)
        ->content($content)
        ->encode(false);
}

            

                public function renderColumn(ColumnInterface $column, Cell $cell, GlobalContext $context): Cell
{
    return $cell->addAttributes($column->columnAttributes);
}

            

                public function renderFooter(ColumnInterface $column, Cell $cell, GlobalContext $context): Cell
{
    if ($column->footer !== null) {
        $cell = $cell->content($column->footer);
    }
    return $cell;
}

            

                public function renderHeader(ColumnInterface $column, Cell $cell, GlobalContext $context): ?Cell
{
    $header = $column->header;
    if ($header === null) {
        if (!$column->multiple) {
            return null;
        }
        $header = Html::checkbox('checkbox-selection-all', 1);
    }
    return $cell
        ->addAttributes($column->headerAttributes)
        ->content($header);
}