Spring NettyHeadersAdapter.add() accepts @Nullable value but throws NullPointerException

NettyHeadersAdapter.add() accepts @Nullable header value, but then calls io.netty.handler.codec.http.HttpHeaders method add, the implementation of which (DefaultHttpHeaders -> DefaultHeaders) throws a NullPointerException if the value is null

I would expect a method accepting a @Nullable value not to throw NPE

Perhaps an if (value != null) check should be implemented in NettyHeadersAdapter.add() before calling HttpHeaders.add() ?

Context: I have a WebFilter that adds the x-request-id header from the request to the response This issue is not easy to predict in testing, because with SpringBootTest.WebEnvironment.MOCK, ServerWebExcahnge.request.headers returns a MultiValueMapAdapter instead of NettyHeadersAdapter, which is indeed null-safe. So I only got NPE when the app was deployed to the server, not in tests