code: @Override
      public PollResult poll(boolean initial, Object checkPoint)
              throws IOException {    
          if (configUrls == null || configUrls.length == 0) {
              return PollResult.createFull(null);
          }
          Map<String, Object> map = new HashMap<String, Object>();
          for (URL url: configUrls) {
              InputStream fin = url.openStream();
              Properties props = ConfigurationUtils.loadPropertiesFromInputStream(fin);
              for (Entry<Object, Object> entry: props.entrySet()) {
                  map.put((String) entry.getKey(), entry.getValue());
              }
          }
          return PollResult.createFull(map);
      }
docs: Retrieve the content of the property files. For each poll, it always
  returns the complete union of properties defined in all URLs. If one
  property is defined in content of more than one URL, the value in file later on the
  list will override the value in the previous one.
  
  @param initial this parameter is ignored by the implementation
  @param checkPoint this parameter is ignored by the implementation
  @throws IOException IOException occurred in file operation