code: @Override
  	public boolean apply(final WarcRecord x) {
  		Header messageType = x.getWarcHeader(WarcHeader.Name.CONTENT_TYPE);
  		return (x.getWarcType() == WarcRecord.Type.RESPONSE) &&
  				(messageType != null && messageType.getValue().equals(HttpResponseWarcRecord.HTTP_RESPONSE_MSGTYPE));
  	}
docs: Apply the filter to a WarcRecord
  
  @param x the <code>WarcRecord</code> to be filtered
  @return <code>true</code> if <code>x</code> is an http/https response.