public Mono<Void> sendMessage(McpSchema.JSONRPCMessage message) {
    if (this.isClosing) {
        return Mono.empty();
    } else {
        try {
            if (!this.closeLatch.await(10L, TimeUnit.SECONDS)) {
                return Mono.error(new McpError("Failed to wait for the message endpoint"));
            }
        } catch (InterruptedException var5) {
            return Mono.error(new McpError("Failed to wait for the message endpoint"));
        }

        String endpoint = (String)this.messageEndpoint.get();
        if (endpoint == null) {
            return Mono.error(new McpError("No message endpoint available"));
        } else {
            try {
                String jsonText = this.objectMapper.writeValueAsString(message);
                HttpRequest request = HttpRequest.newBuilder().uri(URI.create(this.baseUri + endpoint)).header("Content-Type", "application/json").POST(BodyPublishers.ofString(jsonText)).build();
                return Mono.fromFuture(this.httpClient.sendAsync(request, BodyHandlers.discarding()).thenAccept((response) -> {
                    if (response.statusCode() != 200 && response.statusCode() != 201 && response.statusCode() != 202 && response.statusCode() != 206) {
                        logger.error("Error sending message: {}", response.statusCode());
                    }

                }));
            } catch (IOException var6) {
                return !this.isClosing ? Mono.error(new RuntimeException("Failed to serialize message", var6)) : Mono.empty();
            }
        }
    }
}```