public static void copyDirectoryInto(File sourceLocation, File targetLocation) throws IOException {
        File destination = new File(targetLocation, sourceLocation.getAbsoluteFile().getName());
        copyDirectory(sourceLocation, destination);
    }
Copies the whole source directory (infinitely recursively) into the target directory.
@throws IOException if copying any file fails. This will typically result in some files being copied and
        others not, i.e this method is not exception safe
vespajlib/src/main/java/com/yahoo/io/IOUtils.java