Do not use the netdoc URL protocol

The netdoc protocol handler has been removed. Any code that use the netdoc URL protocol to construct a java.net.URL object will result in a MalformedURLException. This rule detects the use of the use of the netdoc URL protocol. For example, the following string will be flagged: netdoc:http://foo.com/index.html.

For more information on the netdoc URL protocol removal, see Java 9 Removed APIs, Features, and Options