Angular 4.3 httpclient empty response headers - django

Question

I have an Django backend. And trying to get http headers from it by using:
1) Angular 4.3 Http (it is going to be deprecated)
2) Plain XmlHttprequest.
3) Angular 4.3 HttpClient
1) and 2) have headers. But 3) does not.
Headers from 1):
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
console.log(this);
console.log(xhttp.getAllResponseHeaders());
}
};
xhttp.open("GET", "http://127.0.0.1:8000/csbg/survey/sometest/", true);
xhttp.send();
Headers from 2):
import { HttpModule} from '#angular/http';
this.http.get('http://127.0.0.1:8000/csbg/survey/sometest/')
.subscribe(
data=>{
console.log('GET OK')
console.log(data)
},
error=>{
console.log("GET ERROR: " + error);
}
)
Headers from (2)
Headers from 3):
import { HttpClient} from '#angular/common/http'
this.http.get('http://127.0.0.1:8000/csbg/survey/sometest/', { observe: 'response' })
.subscribe(
data=>{
console.log('GET OK')
console.log(data)
},
error=>{
console.log("GET ERROR: " + error);
}
)
There is no headers ! Why?
Also, Why default Access-Control-Expose-Headers headers is not present in there:
By default, only the 6 simple response headers are exposed:
Cache-Control
Content-Language
Content-Type
Expires
Last-Modified
Pragma
but my custom header is ?