let requestOptions = new RequestOptions();
    requestOptions.search = serviceParameters;
    requestOptions.withCredentials = true;
return this.http.get(path...., requestOptions)
עובד

    const httpOptions = {
                            headers: new HttpHeaders({
                                                        'Content-Type':  'application/json'                                                      
                                                    })
                          , observable: 'body'
                          , params: null
                          , reportProgress: true                        
                          , withCredentials: true
                        };
    return this.httpClient.post(path..., parms.., httpOptions )
מחזיר 401 (פונה לאותו השרת)

I'm in an Windows env. with NTLM, I got the same problem with CORS. I resolve it by removing headers from the options, it's feels like when adding headers, withCredentials gets overruled! I'm using http 4.3.1
Gives 401
let body = JSON.stringify(data);
let headers = new Headers({'Content-Type': 'application/json'});
let options = new RequestOptions({headers: headers, withCredentials: true});
Works:
let body = JSON.stringify(data);
let options = new RequestOptions({withCredentials: true});

I upgrading from Angularjs to Angular 4, after authentication, I call WS spring to get a list of objects :
angularjs (it's working) : the request header contains a parameter called Cookie, his value include all parameters from Set-Cookie response
angular 4 (KO 401) : Cookie parameter not contains Set-Cookie response parameters.
Using or not header/withCredentials, I have always 401 Unauthorized :
Spring exception : org.springframework.security.authentication.InsufficientAuthenticationException: Full authentication is required to access this resource
this.headers.append( 'Content-Type', 'application/x-www-form-urlencoded' );