throw new AbortException("'mapping' has not been defined for this 'unarchive' step");
for (Entry<String, String> e : step.mapping.entrySet()) {
FilePath dst = new FilePath(ws,e.getValue());
String src = e.getKey();
String[] all = am.root().list(src);
if (all.length == 0) {
throw new AbortException("no artifacts to unarchive in " + src);
} else if (all.length == 1 && all[0].equals(src)) {
// the source is a file
if (dst.isDirectory())