Steps to Reproduce

1. run the code

<charts type="pie" title="中文"/>

2. in built-in export button, select "download PDF document"

Current Result

Expected Result

Chinese characters are correct in PDF

Debug Information

• exported image files don't have such issue

Workaround

• https://github.com/highcharts/highcharts/issues/6417

      // a workaround: change to export PDF via export.highcharts.com instead of local javascript exporting
      // ref: https://github.com/highcharts/highcharts/issues/6417
      Highcharts.wrap(Highcharts.Chart.prototype, 'exportChartLocal', function (proceed, options) {
              if (options && options.type === 'application/pdf') {
           this.exportChart(options);
          } else {
              proceed.call(this, options);
          }
      });