code: @Override
      public void copy(Configuration c)
      {
          if (c != null)
          {
              for (Iterator it = c.getKeys(); it.hasNext();)
              {
                  String key = (String) it.next();
                  Object value = c.getProperty(key);
                  if (key != null && value != null) {
                      setProperty(key, value);
                  }
              }
          }
      }
docs: Copy properties of a configuration into this configuration. This method simply
  iterates the keys of the configuration to be copied and call {@link #setProperty(String, Object)}
  for non-null key/value.