docs: @Override
      public String[] getCacheIDsOnDisk(String cacheInstance, String pattern) throws javax.management.AttributeNotFoundException {
  
          // Get the cache for this cacheInstance
          DCache cache1 = getCache(cacheInstance);
  
          //Throw exception if disk caching is not enabled.  
          if (!cache1.getSwapToDisk()) {
              Tr.error(tc, "DYNA1051E", new Object[] { "getCacheIDsOnDisk", cacheInstance });
              throw new AttributeNotFoundException("Disk caching is not enabled.");
          }
          // Check that the input pattern is a valid regular expression
          Pattern cpattern = checkPattern(pattern);
  
          List<String> matchSet = new ArrayList<String>(10);
          if (cache1.getIdsSizeDisk() > 0) {
              int index = 0;
              boolean more = false;
  
              do {
  
                  more = false;
                  Collection diskSet = cache1.getIdsByRangeDisk(index, 100);
                  if (diskSet != null) {
                      if (true == diskSet.contains(HTODDynacache.DISKCACHE_MORE)) {
                          more = true; //are there any IDs on the disk
                      }
                  }
  
                  index = 1;
                  diskSet.remove(HTODDynacache.DISKCACHE_MORE);
                  Iterator idIterator = diskSet.iterator();
                  while (idIterator.hasNext()) {
                      Object key = idIterator.next();
                      String skey = key.toString();
                      boolean matches = checkMatch(cpattern, skey);
                      if (matches) {
                          matchSet.add(skey);
                          //if (tc.isDebugEnabled()) {
                          //   Tr.debug(tc,"getCacheIDsOnDisk:  Disk Cache id = " +skey + " matches the pattern " + pattern + " for cacheInstance = " + cacheInstance);
                          //}
                      }
                  }
              } while (more == true);
          }
  
          //Allocate output array #entries matched 
          String[] cids = matchSet.toArray(new String[matchSet.size()]);
          if (tc.isDebugEnabled())
              Tr.debug(tc, "getCacheIDsOnDisk: Exiting. Number of matches found = " + matchSet.size());
          return cids;
      }