private static SortedMap<String, Object> makeMap(Map<String, ?> items) {
if (items == null || items.isEmpty())
throw new IllegalArgumentException("Null or empty items map");
SortedMap<String, Object> map = new TreeMap<String, Object>();
for (Object key : items.keySet()) {
if (key == null || key.equals(""))
throw new IllegalArgumentException("Null or empty item name");
if (!(key instanceof String)) {
throw new ArrayStoreException("Item name is not string: " + key);
// This can happen because of erasure. The particular
// exception is a historical artifact - an implementation
// detail that leaked into the API.
}
map.put((String) key, items.get(key));
}
return map;
}
