import static com.google.common.base.Preconditions.checkNotNull;
import java.util.Collection;
+import java.util.Collections;
import java.util.Iterator;
import java.util.Map;
*/
public Collection<Pack> packs() {
synchronized (packs) {
- return packs.values();
+ return Collections.unmodifiableCollection(packs.values());
}
}