Cannot remove headers from httpHeaders.keySet() in WebFlux #26361
Description
Affects: v5.3.2
I have ExchangeFilterFunction which should retain only allowed response headers:
private static final Collection<String> ALLOWED_RESPONSE_HEADERS = Arrays.asList(HttpHeaders.CONTENT_TYPE, HttpHeaders.CONTENT_DISPOSITION); private ExchangeFilterFunction filterResponseHeaders() { return ExchangeFilterFunction.ofResponseProcessor(clientResponse -> Mono.just(ClientResponse.from(clientResponse) .headers(httpHeaders -> httpHeaders.keySet().removeIf(headerName -> !ALLOWED_RESPONSE_HEADERS.contains(headerName))) .body(clientResponse.bodyToFlux(DataBuffer.class)) .build())); }This one is working correctly.
Because of ClientResponse.from() deprecation, the method is rewritten to:
private ExchangeFilterFunction filterResponseHeaders() { return ExchangeFilterFunction.ofResponseProcessor(clientResponse -> Mono.just(clientResponse.mutate() .headers(httpHeaders -> httpHeaders.keySet().removeIf(headerName -> !ALLOWED_RESPONSE_HEADERS.contains(headerName))) .build())); }That one is not working. Response headers are not affected.