如何移除Highcharts X-Range图表中系列间的间距与内边距？

我尝试移除Highcharts X-Range图表中系列间的额外间距/内边距，目的是让分属不同系列的数据点对应正确的Y轴值。仅使用单个系列时显示正常，但添加第二个系列后所有元素出现偏移。官方文档显示设置pointPlacement: 'on'可解决该问题，但实际无效。

双系列示例（Y轴位置错误） #

Highcharts.chart('container', {
    chart: {
        type: 'xrange',
        pointPlacement: 'on'
    },
    title: {
        text: 'Highcharts X-range'
    },
    plotOptions: {
      series: {
        pointPlacement: 'on'
      }
    },
    xAxis: {
        type: 'datetime',
        min: Date.UTC(2014, 10, 21, 0, 0),
        max: Date.UTC(2014, 10, 21, 24, 0),
        gridLineWidth: 1,
        labels: {
            format: '{value:%H}',
            tickInterval: 3600 * 1000
        }
    },
    yAxis: {
          gridLineWidth: 1,
        min: 0,
        title: {
            enabled:false
        }
    },
    series: [{
        name: 'Project 1',
        className: "series_0",
        pointPadding: 0,
        pointWidth: 5,
        groupPadding: 0,
        data: [
            {
            x: Date.UTC(2014, 10, 21, 4, 15),
            x2: Date.UTC(2014, 10, 21, 19, 15),
            y: 1
        },{
            x: Date.UTC(2014, 10, 21, 4, 15),
            x2: Date.UTC(2014, 10, 21, 19, 15),
            y: 2
        }, 
        ],
        dataLabels: {
            enabled: true
        }
    },
    {
        name: 'Project 2',
        className: "series_1",
        pointPadding: 0,
        pointWidth: 5,
        groupPadding: 0,
        data: [
            {
            x: Date.UTC(2014, 10, 21, 4, 15),
            x2: Date.UTC(2014, 10, 21, 19, 15),
            y: 3
        },{
            x: Date.UTC(2014, 10, 21, 4, 15),
            x2: Date.UTC(2014, 10, 21, 19, 15),
            y: 4
        }, 
        ],
        dataLabels: {
            enabled: true
        }
    }
    ]
});

单系列示例（Y轴位置正确） #

Highcharts.chart('container', {
    chart: {
        type: 'xrange',
        pointPlacement: 'on'
    },
    title: {
        text: 'Highcharts X-range'
    },
    plotOptions: {
      series: {
        pointPlacement: 'on'
      }
    },
    xAxis: {
        type: 'datetime',
        min: Date.UTC(2014, 10, 21, 0, 0),
        max: Date.UTC(2014, 10, 21, 24, 0),
        gridLineWidth: 1,
        labels: {
            format: '{value:%H}',
            tickInterval: 3600 * 1000
        }
    },
    yAxis: {
          gridLineWidth: 1,
        min: 0,
        title: {
            enabled:false
        }
    },
    series: [{
        name: 'Project 1',
        className: "series_0",
        pointPadding: 0,
        pointWidth: 5,
        groupPadding: 0,
        data: [
            {
            x: Date.UTC(2014, 10, 21, 4, 15),
            x2: Date.UTC(2014, 10, 21, 19, 15),
            y: 1
        },{
            x: Date.UTC(2014, 10, 21, 4, 15),
            x2: Date.UTC(2014, 10, 21, 19, 15),
            y: 2
        }, 
        ],
        dataLabels: {
            enabled: true
        }
    }
    ]
});

内容的提问来源于stack exchange，提问作者ThisIsMe