message: App: Remove obsolete authHeaders in BackendService
diff: import {Observable} from 'rxjs/Observable';
  import {Injectable} from '@angular/core';
  -import {HttpClient} from '@angular/common/http';
  +import {HttpClient, HttpHeaders} from '@angular/common/http';
  import {AuthenticationService} from './authentication.service';
  import {catchError} from 'rxjs/operators';
  import {throwError} from 'rxjs/index';
  @@ -23,8 +23,12 @@ export class BackendService {
  return throwError(err);
  }
  + private get defaultHttpClientOptions () {
  + return {headers: new HttpHeaders({'Content-Type': 'application/json'})};
  + }
  +
  head(serviceUrl: string): Observable<any> {
  - return this.http.head(BackendService.API_URL + serviceUrl, {headers: this.authenticationService.authHeader(),
  + return this.http.head(BackendService.API_URL + serviceUrl, {...this.defaultHttpClientOptions,
  observe: 'response', responseType: 'blob'})
  .pipe(catchError(this.handleUnauthorized));
  }
  @@ -35,34 +39,33 @@ export class BackendService {
  }
  get(serviceUrl: string): Observable<any> {
  - return this.http.get(BackendService.API_URL + serviceUrl, {headers: this.authenticationService.authHeader()})
  + return this.http.get(BackendService.API_URL + serviceUrl, this.defaultHttpClientOptions)
  .pipe(catchError(this.handleUnauthorized));
  }
  getDownload(serviceUrl: string): Observable<any> {
  - return this.http.get(BackendService.API_URL + serviceUrl, {headers: this.authenticationService.authHeader(),
  + return this.http.get(BackendService.API_URL + serviceUrl, {...this.defaultHttpClientOptions,
  observe: 'response', responseType: 'blob'})
  .pipe(catchError(this.handleUnauthorized));
  }
  - post(serviceUrl: string, options: any): Observable<any> {
  - return this.http.post(BackendService.API_URL + serviceUrl, options, {headers: this.authenticationService.authHeader()})
  + post(serviceUrl: string, body: any): Observable<any> {
  + return this.http.post(BackendService.API_URL + serviceUrl, body, this.defaultHttpClientOptions)
  .pipe(catchError(this.handleUnauthorized));
  }
  - put(serviceUrl: string, options: any): Observable<any> {
  - return this.http.put(BackendService.API_URL + serviceUrl, options, {headers: this.authenticationService.authHeader()})
  + put(serviceUrl: string, body: any): Observable<any> {
  + return this.http.put(BackendService.API_URL + serviceUrl, body, this.defaultHttpClientOptions)
  .pipe(catchError(this.handleUnauthorized));
  }
  delete(serviceUrl: string): Observable<any> {
  - return this.http.delete(BackendService.API_URL + serviceUrl, {headers: this.authenticationService.authHeader()})
  + return this.http.delete(BackendService.API_URL + serviceUrl, this.defaultHttpClientOptions)
  .pipe(catchError(this.handleUnauthorized));
  }
  onBeforeUpload(event: any, id: string, extension: string) {
  - event.xhr.setRequestHeader('Authorization', this.authenticationService.token);
  event.xhr.setRequestHeader('uploadfilename', id + '.' + extension);
  }
  }
  