public static void copy(File inFile, File outFile) throws IOException {
        try (FileChannel sourceChannel = new FileInputStream(inFile).getChannel();
             FileChannel destChannel = new FileOutputStream(outFile).getChannel()) {
            destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
        }
    }
Copies a file to another file.
If the out file exists it will be overwritten.
vespajlib/src/main/java/com/yahoo/io/IOUtils.java