I was playing around with AssetLoader and I found that the order of builder arguments matters. I found this extremely surprising, and this is not the normal convention for builders. As an example, here are two pieces of Java code which do different things:

// Code snippet 1...

        final WebViewAssetLoader assetLoader = new WebViewAssetLoader.Builder()

                // Set the domain first and everything works!
                .setDomain("www.fakedomain.com")

                .addPathHandler("/assets/", new WebViewAssetLoader.AssetsPathHandler(this))
                .addPathHandler("/res/", new WebViewAssetLoader.ResourcesPathHandler(this))
                .build();
        mWebView.setWebViewClient(new LocalContentWebViewClient(assetLoader));
        String inAppHtmlUrl = "https://www.fakedomain.com/assets/index.html";
        mWebView.loadUrl(inAppHtmlUrl);

// Code snippet 2...

        final WebViewAssetLoader assetLoader = new WebViewAssetLoader.Builder()
                .addPathHandler("/assets/", new WebViewAssetLoader.AssetsPathHandler(this))
                .addPathHandler("/res/", new WebViewAssetLoader.ResourcesPathHandler(this))

                // But if we set the domain after PathHandlers, WebView tries to load from the internet
                .setDomain("www.fakedomain.com")

                .build();
        mWebView.setWebViewClient(new LocalContentWebViewClient(assetLoader));
        String inAppHtmlUrl = "https://www.fakedomain.com/assets/index.html";
        mWebView.loadUrl(inAppHtmlUrl);

The issue is we dereference the mDomain when addPathHandler is called, but we really should wait until .build() is called. Same problem with mHttpAllowed. See https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:webkit/webkit/src/main/java/androidx/webkit/WebViewAssetLoader.java;l=526;drc=764112d6d736023c63322b262bec9c93e67786ca

Issue 182196765

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