WebView.loadUrl raising UnsupportedOperationException

Question

This exception raising only in android 5.1 (Samsung galaxy J3 2016)

Log:

Caused by java.lang.UnsupportedOperationException
    java.util.Collections$SingletonMap$1$1.remove (Collections.java:355)
    java.util.AbstractMap.remove (AbstractMap.java:397)
    org.chromium.android_webview.AwContents.loadUrl (AwContents.java:1594)
    org.chromium.android_webview.AwContents.loadUrl (AwContents.java:1458)
    com.android.webview.chromium.WebViewChromium.loadUrl (WebViewChromium.java:496)
    android.webkit.WebView.loadUrl (WebView.java:862)

I don't have this device, I receive a ton of such exceptions from my crashlytics report. My WebView settings is below:

settings.loadWithOverviewMode = true
settings.useWideViewPort = true
@SuppressLint("SetJavaScriptEnabled")
settings.javaScriptEnabled = true
settings.domStorageEnabled = true
webViewClient = WebViewClient()

And I am loading URL with extra headers provided:

val extraHeaders = mapOf("Referer" to "https://my.site.url")
webView.loadUrl(state.url, extraHeaders)

Answer 1

Ok, I found a problem: In source code of AwContents in loadUrl method you can find such block:

    final String REFERER = "referer";
    Map<String, String> extraHeaders = params.getExtraHeaders();
    if (extraHeaders != null) {
        for (String header : extraHeaders.keySet()) {
            if (REFERER.equals(header.toLowerCase(Locale.US))) {
                params.setReferrer(new Referrer(extraHeaders.remove(header), 1));
                params.setExtraHeaders(extraHeaders);
                break;
            }
        }
    }

interesting thing is extraHeaders.remove(header) because I'm creating immutable map, this causing throwing UnsupportedOperationException.

Made this change:

val extraHeaders = mutableMapOf("Referer" to "https://my.site.url")