When using WebView can not set Referer header.
For any other header name it is working.

Device name: 
Android version: 4.4.4, 5.0, 6.0
WebView version (from system settings -> Apps -> Android System WebView): 52.0.2743.98, 53.0.2785.90
Application: 
Application version:

URLs (if applicable):

Steps to reproduce:
        final Map<String, String> extraHeaders = new HashMap<>(1);
        extraHeaders.put("Referer", "android-app://my.referer");
        webView.loadUrl("https://www.whatismyreferer.com/", extraHeaders);

Expected result:
Referer header should be set

Actual result:
Referer header is not set