要获取Apache Curator GroupMember的完整成员集合，可以使用GroupMember#getMembers方法。以下是一个示例代码：

import org.apache.curator.framework.CuratorFramework;
import org.apache.curator.framework.CuratorFrameworkFactory;
import org.apache.curator.retry.ExponentialBackoffRetry;
import org.apache.curator.x.discovery.ServiceDiscovery;
import org.apache.curator.x.discovery.ServiceDiscoveryBuilder;
import org.apache.curator.x.discovery.ServiceInstance;
import org.apache.curator.x.discovery.details.JsonInstanceSerializer;
import org.apache.curator.x.discovery.details.ServiceCacheListener;
import org.apache.curator.x.discovery.details.ServiceCacheProvider;
import org.apache.curator.x.discovery.details.ServiceDiscoveryImpl;
import org.apache.curator.x.discovery.details.ServiceInstanceSerializer;

import java.util.Collection;
import java.util.concurrent.TimeUnit;

public class CuratorGroupMemberExample {

    public static void main(String[] args) throws Exception {
        // 创建CuratorFramework客户端
        CuratorFramework curatorFramework = CuratorFrameworkFactory.newClient("localhost:2181", new ExponentialBackoffRetry(1000, 3));
        curatorFramework.start();

        // 创建ServiceDiscovery
        ServiceInstanceSerializer serializer = new JsonInstanceSerializer<>(ServiceDetails.class);
        ServiceDiscovery serviceDiscovery = ServiceDiscoveryBuilder.builder(ServiceDetails.class)
                .client(curatorFramework)
                .basePath("/services")
                .serializer(serializer)
                .build();

        // 启动ServiceDiscovery
        serviceDiscovery.start();

        // 创建GroupMember，并监听成员变化
        GroupMember groupMember = new GroupMember(curatorFramework, "/group", "member1");
        groupMember.start();

        // 获取完整的成员集合
        Collection members = groupMember.getMembers();
        System.out.println("Members: " + members);

        // 关闭GroupMember和ServiceDiscovery
        groupMember.close();
        serviceDiscovery.close();
        curatorFramework.close();
    }

    static class GroupMember implements ServiceCacheListener {
        private final CuratorFramework curatorFramework;
        private final String path;
        private final String memberId;
        private final ServiceCacheProvider cacheProvider;

        public GroupMember(CuratorFramework curatorFramework, String path, String memberId) {
            this.curatorFramework = curatorFramework;
            this.path = path;
            this.memberId = memberId;
            this.cacheProvider = ServiceDiscoveryImpl.createCacheProvider(curatorFramework, path);
        }

        public void start() throws Exception {
            cacheProvider.start();
            cacheProvider.addCacheListener(this);
        }

        public void close() throws Exception {
            cacheProvider.close();
        }

        public Collection getMembers() {
            return cacheProvider.getInstances().keySet();
        }

        @Override
        public void cacheChanged() {
            Collection> instances = cacheProvider.getInstances().values();
            for (ServiceInstance instance : instances) {
                System.out.println("Member: " + instance.getName());
            }
        }
    }

    static class ServiceDetails {
        // 定义服务的详细信息
    }
}

在上面的示例代码中，我们首先创建一个CuratorFramework客户端，并启动它。然后，我们创建一个ServiceDiscovery实例，用于发现和管理服务。接下来，我们创建一个GroupMember实例，并指定要加入的组路径和成员ID。然后，我们启动GroupMember实例，并监听成员变化。通过调用GroupMember#getMembers方法，我们可以获取完整的成员集合。

注意：上述示例中使用的ServiceDiscovery和ServiceDetails是Apache Curator提供的服务注册和发现功能的相关类，您需要根据实际情况进行相应的调整。