Highcharts => Getting the id of a point when clicking on a line chart

I am building a line chart and I would like, when I click on a point of the line, to display a popup containing some data about this point. The issue I try to resolve is to get the id, the series associated with this point or something like that.

Here is my code :

plotOptions: {
      column: {
        pointWidth: 20
      },

      series: {
        cursor: 'pointer',
        events: {
          click: function(event) {
            requestData(event.point);
          }
        }
      }

I tried

requestData(this.point)

,

requestData(this.point.id)

also but it doesn't work.

How do we get the id of a point ?

Thanks a lot.