code: @Override
  	public CEMILData request(final KNXAddress dst, final Configuration c)
  	{
  		final Cache cache = c.getCache();
  		if (cache == null || !(dst instanceof GroupAddress))
  			return null;
  		final LDataObject o = (LDataObject) cache.get(dst);
  		if (o == null)
  			return null;
  		// check if there is an expiration timeout for a state based value
  		final Datapoint dp;
  		final DatapointModel<?> m = c.getDatapointModel();
  		if (m != null && (dp = m.get((GroupAddress) dst)) != null && dp.isStateBased()) {
  			final int t = ((StateDP) dp).getExpirationTimeout() * 1000;
  			if (t != 0 && System.currentTimeMillis() > o.getTimestamp() + t)
  				return null;
  		}
  		return o.getFrame();
  	}
docs: /* (non-Javadoc)
  @see tuwien.auto.calimero.buffer.Configuration.RequestFilter#request(
  tuwien.auto.calimero.KNXAddress, tuwien.auto.calimero.buffer.Configuration)