检测到Angular 4 Circular依赖性

WARNING in Circular dependency detected:
srcappwork-sessionswork-session-listwork-session-list.routing.ts -> srcappwork-sessionswork-session-listindex.ts -> srcappwork
-sessionswork-session-listwork-session-list.routing.ts

每个类都有这样的结构：

工作会话list.routing.ts

import { Route } from '@angular/router';
import { WorkSessionListComponent } from './index';

export const WorkSessionRoutes: Route[] = [
  {
    path: '',component: WorkSessionListComponent
  },];

Index.ts

export * from './work-session-list.component';
export * from './work-session-list.routing';

工作会议,list.module.ts

import { WorkSessionListComponent } from './work-session-list.component';
import { WorkSessionRoutes } from './work-session-list.routing';
import { DataTableModule } from 'primeng/primeng';
import { CommonModule } from '@angular/common';
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { RouterModule } from '@angular/router';

@NgModule( {
    imports: [RouterModule.forChild( WorkSessionRoutes ),CommonModule,FormsModule],declarations: [WorkSessionListComponent],exports: [WorkSessionListComponent]
} )

export class WorkSessionListModule { }

比在app.routing.ts

export const AppRoutes: Routes = [
      {
        path: 'workSession',loadChildren: './work-sessions/work-session-list/work-session-list.module#WorkSessionListModule'
      }
.
.
.

在app.module中

@NgModule({
imports: [
CommonModule,BrowserAnimationsModule,FormsModule,RouterModule.forRoot(AppRoutes),})
  ],declarations: [
    AppComponent
  ]
  bootstrap: [AppComponent]
})
export class AppModule {}

我怎么解决这个问题？它有效,但我有很多警告