code: public static HttpResponse fromPublisher(HttpHeaders headers,
                                               Publisher<? extends ServerSentEvent> contentPublisher,
                                               HttpHeaders trailingHeaders) {
          requireNonNull(headers, "headers");
          requireNonNull(contentPublisher, "contentPublisher");
          requireNonNull(trailingHeaders, "trailingHeaders");
          return streamingFrom(contentPublisher, sanitizeHeaders(headers), trailingHeaders,
                               ServerSentEvents::toHttpData);
      }
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
  @param trailingHeaders the trailing HTTP headers supposed to send