Project specific browsersync configuration with reverse proxy (https://github.com/mgechev/angular2-seed/blob/master/tools/config/project.config.ts)

project.config.ts

const proxy = require('proxy-middleware');

import {join} from 'path';
import {SeedConfig} from './seed.config';
import {InjectableDependency} from './seed.config.interfaces';

export class ProjectConfig extends SeedConfig {
  PROJECT_TASKS_DIR = join(process.cwd(), this.TOOLS_DIR, 'tasks', 'project');

  constructor() {
    super();
    // this.APP_TITLE = 'Put name of your app here';

    // add reverse proxy here
    this.BROWSER_SYNC_CONFIG = {
      port: this.PORT,
      startPath: this.APP_BASE,
      server: {
        baseDir: `${this.DIST_DIR}/empty/`,
        middleware: [
          proxy({
            protocol: 'http:',
            hostname: 'localhost',
            port: 8080,
            pathname: '/api',
            route: '/api'
          }),
          require('connect-history-api-fallback')({index: `${this.APP_BASE}index.html`})
        ],
        routes: {
          [`${this.APP_BASE}${this.APP_DEST}`]: this.APP_DEST,
          [`${this.APP_BASE}node_modules`]: 'node_modules',
          [`${this.APP_BASE.replace(/\/$/,'')}`]: this.APP_DEST
        }
      }
    };

    let additional_deps: InjectableDependency[] = [
      // {src: 'jquery/dist/jquery.min.js', inject: 'libs'},
      // {src: 'lodash/lodash.min.js', inject: 'libs'},
    ];

    const seedDependencies = this.NPM_DEPENDENCIES;

    this.NPM_DEPENDENCIES = seedDependencies.concat(additional_deps);
  }
}

Does this work with the most recent version of the seed too? I can't get it working.. I get the following error during compilation:
Property 'BROWSER_SYNC_CONFIG' does not exist on type 'ProjectConfig'.
For me it seems that browser sync config are now managed in a different way as shown here:
https://github.com/mgechev/angular2-seed/blob/master/tools/config/seed.config.ts#L421