I can't able to get the response from the server using angular httpclientmodule,
I'm completely new to angular6 httpclientmodule, please find the below code

myservice.ts

```
import { Injectable } from '@angular/core';
import {Observable} from "rxjs/Observable";
import {HttpClient, HttpHeaders} from "@angular/common/http";
import { map } from 'rxjs/operators';
import { Headers, RequestOptions } from '@angular/http';
import 'rxjs/Rx';

@Injectable({
  providedIn: 'root'
})
export class MyserviceService {

  response: any;
  constructor(private http: HttpClient) { }

 getLogin(mobileNumber, loginPassword) {
  let headers= new HttpHeaders().set('Content-Type','application/json').set('X-Authorization','clientmobileClient1').set('username',mobileNumber).set('password',loginPassword);
    return this.http.post('http://My API URL', null, {headers}).map((response: any) => response.json());

  }
}

```

mycomponent.ts

```
 onSubmit() {
    this.service.getLogin(mobileNumber, loginPassword).subscribe((response: any) => { console.log("my response", response) });
}

```

Please help me out where I'm wrong.

thanks