如何在ng2-charts中动态使用chartjs-plugin-annotation？

npm install ng2-charts chart.js --save

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppComponent } from './app.component';

import { ChartsModule } from 'ng2-charts';
import { ChartModule } from 'chart.js';

@NgModule({
  imports:      [ BrowserModule, FormsModule, ChartsModule, ChartModule ],
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})
export class AppModule { }

import { Component, OnInit } from '@angular/core';
import { ChartDataSets, ChartOptions } from 'chart.js';
import { Color, Label } from 'ng2-charts';

import 'chartjs-plugin-annotation';

@Component({
  selector: 'app-your-component',
  templateUrl: './your-component.component.html',
  styleUrls: ['./your-component.component.css']
})
export class YourComponent implements OnInit {
  public lineChartData: ChartDataSets[] = [
    { data: [85, 72, 78, 75, 77, 75], label: 'Series A' },
  ];
  public lineChartLabels: Label[] = ['January', 'February', 'March', 'April', 'May', 'June'];
  public lineChartOptions: ChartOptions = {
    responsive: true,
    annotation: {
      annotations: [{
        type: 'line',
        mode: 'vertical',
        scaleID: 'x-axis-0',
        value: 'March',
        borderColor: 'orange',
        borderWidth: 2,
        label: {
          enabled: true,
          fontColor: 'orange',
          content: 'Annotation Label'
        }
      }],
    },
  };
  public lineChartColors: Color[] = [
    {
      borderColor: 'black',
      backgroundColor: 'rgba(255,255,0,0.28)',
    },
  ];
  public lineChartLegend = true;
  public lineChartPlugins = [];
  public lineChartType = 'line';

  constructor() { }

  ngOnInit() {
  }

}

<div style="display: block">
  <canvas baseChart
          [datasets]="lineChartData"
          [labels]="lineChartLabels"
          [options]="lineChartOptions"
          [colors]="lineChartColors"
          [legend]="lineChartLegend"
          [plugins]="lineChartPlugins"
          [chartType]="lineChartType"></canvas>
</div>