Angular - Shared Services

When I log in, I get the authentication token. I'm using the getHeaders() function by passing the authentication token I get from the backend as a parameter to insert it in header .

  

shared.service.ts

import { Injectable } from '@angular/core';
import { RequestOptions } from '@angular/http';

@Injectable()

export class SharedService {
    headers;
    url = 'http://localhost:8000/api/';

    constructor() {
        this.headers = '';
    }

    setHead(token: string){
        this.headers = new Headers({
            'Authorization': 'Bearer ' + token,
            'Content-Type': 'application/json'
        });
    }

    getHead(){
        return new RequestOptions({ headers: this.headers });
    }
}

  

app.module.ts

import { SharedService } from './shared.service';

@NgModule({
bootstrap: [AppComponent],
providers: [
    ...
    SharedService,
],
export class AppModule {
}

  

app.components.ts

constructor(
    private authService: NbAuthService,
    private sharedService: SharedService
) {
    this.authService.onTokenChange()
    .subscribe((token: NbAuthJWTToken) => {
        if(token.isValid()){
            this.sharedService.setHead(token.toString());
        }
    });
}

However, giving console.log(this.sharedService.getHead()) header does not return Content-Type: application/json and Authorization: Bearer ... . It contains only __proto__ :

  

console.log return

body : null
headers : Headers
    __proto__ : Headers
method : null
params : undefined
responseType : null
search : (...)
url : null
withCredentials : null
__proto__ : Object