The `netdoc` protocol handler has been removed in JDK 9. Code that attempts to construct a `java.net.URL` with the `netdoc` protocol, for example "netdoc:http://foo.com/index.html" will throw a `MalformedURLException`.

The `netdoc` protocol was used to point to network documents either on the local file system or externally through an HTTP URL. This capability is essentially defunct and is not supported by Safari, Firefox, and other major browsers.