title: How to pass a param to HttpInterceptor?
body: <p>I am using Angular 4.3.1 and HttpClient. There is an HttpInterceptor to set some headers. </p>
  
  <p>In some http get requests I need to set a different header. Is there anyway I can pass some param to this HttpInterceptor for that particular HttpRequest?</p>
  
  <pre><code>@Injectable()
  export class MyHttpInterceptor implements HttpInterceptor {
  
    intercept(request: HttpRequest&lt;any&gt;, next: HttpHandler): Observable&lt;HttpEvent&lt;any&gt;&gt; {
      if(request.custom.param1) // how can i do this 
        request = request.clone({
          setHeaders: {
            'header1': 'xxxxxx'
            }
        });
  
      else
        request = request.clone({
          setHeaders: {
            'header2': 'yyyyyy'
            }
        });
  
  
      return next.handle(request);
    }
  }
  </code></pre>