/**
  * Extract core names.
  *
  * @param cores All the available cores.
  * @return The core's name.
  */
 private static Iterable<String> coreNames(final CoreContainer cores) {
   List<String> names = new ArrayList<String>();
   for (SolrCore core : cores.getCores()) {
     String name = core.getName();
     if (isEmpty(name)) {
       // This is the default core.
       name = cores.getDefaultCoreName();
     }
     names.add(name);
   }
   return names;
 }