@Override
                public Void run() {
                    final FileSystem hdfs = getHDFS(conf);

                    // run the passed lambda
                    func.accept(hdfs);

                    return null;
                }
Creates an output stream for a file on an Hadoop Distributed File System
<p>
TODO Need to add in proper security so it can connect to a secured
(kerberos?) cluster
stroom-pipeline/src/main/java/stroom/pipeline/writer/HDFSFileAppender.java