code: public static HttpResponse fromPublisher(HttpHeaders headers,
                                               Publisher<? extends ServerSentEvent> contentPublisher) {
          return fromPublisher(headers, contentPublisher, HttpHeaders.EMPTY_HEADERS);
      }
docs: Creates a new Server-Sent Events stream from the specified {@link Publisher}.
  
  @param headers the HTTP headers supposed to send
  @param contentPublisher the {@link Publisher} which publishes the objects supposed to send as contents