/usr/share/doc/openjdk-9-jre-headless/examples/nio/ is in openjdk-9-demo 9~b114-0ubuntu1.
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..
/usr/share/doc/openjdk-9-jre-headless/examples/nio/chatserver/
/usr/share/doc/openjdk-9-jre-headless/examples/nio/chatserver/ChatServer.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/chatserver/Client.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/chatserver/ClientReader.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/chatserver/DataReader.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/chatserver/MessageReader.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/chatserver/NameReader.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/chatserver/README.txt
/usr/share/doc/openjdk-9-jre-headless/examples/nio/file/
/usr/share/doc/openjdk-9-jre-headless/examples/nio/file/AclEdit.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/file/Chmod.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/file/Copy.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/file/DiskUsage.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/file/FileType.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/file/WatchDir.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/file/Xdd.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/multicast/
/usr/share/doc/openjdk-9-jre-headless/examples/nio/multicast/MulticastAddress.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/multicast/Reader.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/multicast/Sender.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/AcceptHandler.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/Acceptor.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/B1.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/BN.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/BP.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/ChannelIO.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/ChannelIOSecure.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/Content.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/Dispatcher.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/Dispatcher1.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/DispatcherN.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/FileContent.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/Handler.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/MalformedRequestException.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/N1.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/N2.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/README.txt
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/Reply.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/Request.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/RequestHandler.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/RequestServicer.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/Sendable.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/Server.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/StringContent.java
/usr/share/doc/openjdk-9-jre-headless/examples/nio/server/URLDumper.java