code: private static UriComponentsBuilder getBuilder(@Nullable ServerWebExchange exchange) {
  
  		return exchange == null //
  				? UriComponentsBuilder.fromPath("/") //
  				: UriComponentsBuilder.fromHttpRequest(exchange.getRequest());
  	}
docs: Returns a {@link UriComponentsBuilder} obtained from the {@link ServerWebExchange}.
  
  @param exchange