如何使用PhpSpreadsheet将数组数据导出并合并行生成Excel表格？

[
    "customer" => "西卡若卡",
    "product" => [
        [
            "name" => "瓶-500ml塑料瓶",
            "parts" => "24牙35克",
            "rongliang" => "500ml"
        ],
        [
            "name" => "内塞-500ml塑料瓶",
            "parts" => "19小孔内塞+盖板",
        ],
        [
            "name" => "盖子-500ml塑料瓶",
            "parts" => "24牙双层pp盖",
        ],
    ]
]

use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;

$spreadsheet = new Spreadsheet();
$sheet = $spreadsheet->getActiveSheet();

$data = [
    "customer" => "西卡若卡",
    "product" => [
        [
            "name" => "瓶-500ML塑料瓶",
            "parts" => "24牙35克",
            "rongliang" => "500ML"
        ],
        [
            "name" => "内塞-500ML塑料瓶",
            "parts" => "19小孔内塞+盖板",
        ],
        [
            "name" => "盖子-500ML塑料瓶",
            "parts" => "24牙双层PP盖",
        ],
    ]
];

$sheet->setCellValue('A1', '客户');
$sheet->setCellValue('B1', '产品名称');
$sheet->setCellValue('C1', '部件');
$sheet->setCellValue('D1', '容量');

$row = 2;
foreach ($data['product'] as $product) {
    $sheet->setCellValue('A' . $row, $data['customer']);
    $sheet->setCellValue('B' . $row, $product['name']);
    $sheet->setCellValue('C' . $row, $product['parts']);
    if (isset($product['rongliang'])) {
        $sheet->setCellValue('D' . $row, $product['rongliang']);
    }
    $row++;
}

// 合并客户列
$sheet->mergeCells('A2:A' . ($row - 1));

$writer = new Xlsx($spreadsheet);
$writer->save('example.xlsx');