chartjs:如何为堆叠条形图创建单个外部边框

<canvas id="myChart"></canvas>

var ctx = document.getElementById('myChart').getContext('2d');
var myChart = new Chart(ctx, {
    type: 'bar',
    data: {
        labels: ['标签1', '标签2', '标签3'],
        datasets: [
            {
                label: '数据集1',
                data: [10, 20, 30],
                backgroundColor: 'rgba(255, 99, 132, 0.5)',
                borderColor: 'rgba(255, 99, 132, 1)',
                borderWidth: 1
            },
            {
                label: '数据集2',
                data: [15, 25, 35],
                backgroundColor: 'rgba(54, 162, 235, 0.5)',
                borderColor: 'rgba(54, 162, 235, 1)',
                borderWidth: 1
            }
        ]
    },
    options: {
        scales: {
            x: {
                stacked: true
            },
            y: {
                stacked: true
            }
        },
        plugins: {
            legend: {
                display: false
            }
        }
    }
});