使用ActiveMQ Artemis REST API发送带有群组ID的消息，可以使用HTTP POST请求来发送消息。以下是一个示例代码，演示如何使用Java和HttpClient库发送POST请求：

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import java.io.IOException;

public class ArtemisRestExample {
    public static void main(String[] args) {
        String url = "http://localhost:8161/rest/queues/your-queue-name/messages";
        String brokerUsername = "admin";
        String brokerPassword = "admin";
        String groupId = "your-group-id";
        String message = "Your message";

        CloseableHttpClient httpClient = HttpClients.createDefault();
        HttpPost httpPost = new HttpPost(url);

        // Set Basic Authentication credentials
        httpPost.setHeader("Authorization", "Basic " + Base64.getEncoder().encodeToString((brokerUsername + ":" + brokerPassword).getBytes()));

        // Set content type and message body
        httpPost.setHeader("Content-Type", "application/json");
        StringEntity requestEntity = new StringEntity("{\"message\": \"" + message + "\", \"groupId\": \"" + groupId + "\"}", ContentType.APPLICATION_JSON);
        httpPost.setEntity(requestEntity);

        try (CloseableHttpResponse response = httpClient.execute(httpPost)) {
            HttpEntity responseEntity = response.getEntity();
            if (responseEntity != null) {
                System.out.println("Response status: " + response.getStatusLine());
                System.out.println("Response body: " + EntityUtils.toString(responseEntity));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

请注意，上述示例中的URL应该替换为您的ActiveMQ Artemis REST API的实际URL，brokerUsername和brokerPassword应该替换为您的ActiveMQ Artemis经纪人的用户名和密码，your-queue-name应该替换为您要将消息发送到的队列的名称，your-group-id应该替换为您要设置的群组ID，message应该替换为您要发送的消息内容。

此代码示例使用Apache HttpClient库来发送POST请求，并在请求头中设置了Basic身份验证凭据。它还设置了请求的内容类型为application/json，并使用StringEntity将消息和群组ID作为JSON字符串发送。

注意：在使用ActiveMQ Artemis REST API发送消息之前，您需要确保已在ActiveMQ Artemis服务器上启用了REST接口，并且具有正确的身份验证凭据。