Load accordion with DataSource in Angular Accordion component

import { Component, OnInit, ViewChild } from '@angular/core';
import { AccordionComponent } from '@syncfusion/ej2-angular-navigations';
import { DataManager, Query, ODataAdaptor, ReturnOption } from '@syncfusion/ej2-data';

const SERVICE_URI: string = 'https://js.syncfusion.com/ejServices/Wcf/Northwind.svc/Employees';

@Component({
    selector: 'app-container',
    template: `<ejs-accordion #element></ejs-accordion>`
})

export class AppComponent implements OnInit {
  @ViewChild('element') accordionObj: AccordionComponent;
  public itemsData: any = [];
  public mapping =  { header: 'FirstName', content: 'Notes' };

  public ngOnInit(): void {
    new DataManager({ url: SERVICE_URI, adaptor: new ODataAdaptor})
    .executeQuery(new Query().range(1, 4)).then((e: ReturnOption) => {
      let result: any = e.result;

      for(let i: number = 0; i < result.length; i++) {
        this.itemsData.push({ header: result[i][this.mapping.header], content: result[i][this.mapping.content] });
      }
      this.accordionObj.items = this.itemsData;
      this.accordionObj.refresh();
    });
  }
}

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AccordionModule } from '@syncfusion/ej2-angular-navigations';
import { AppComponent } from './app.component';

/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule, AccordionModule
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent]
})
export class AppModule { }

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

enableProdMode();
platformBrowserDynamic().bootstrapModule(AppModule);