[Bugfix]修复ConsumerAssignment类型转换错误的问题

1、问题
KSGroupDescription 的 KSMemberBaseAssignment 对象，转 KSMemberConsumerAssignment 时，会出现转换失败的错误。

2、原因
KSPartialKafkaAdminClient 在返回 KSMemberDescription 时，当 ConsumerGroup 的 memberAssignment.length() <= 0 时，遗漏对 memberBaseAssignment 对象进行初始化。

3、解决
发现 memberAssignment.length() <= 0 时，主动将 KSMemberDescription 中的 memberBaseAssignment 赋值为 KSMemberConsumerAssignment 对象。

km-biz/src/main/java/com/xiaojukeji/know/streaming/km/biz/group/impl/GroupManagerImpl.java

@@ -168,9 +168,10 @@ public class GroupManagerImpl implements GroupManager {
         // 转换存储格式
         Map<TopicPartition, KSMemberDescription> tpMemberMap = new HashMap<>();
 
-        //如果不是connect集群
+        // 如果不是connect集群
         if (!groupDescription.protocolType().equals(CONNECT_CLUSTER_PROTOCOL_TYPE)) {
             for (KSMemberDescription description : groupDescription.members()) {
+                // 如果是 Consumer 的 Description ，则 Assignment 的类型为 KSMemberConsumerAssignment 的
                 KSMemberConsumerAssignment assignment = (KSMemberConsumerAssignment) description.assignment();
                 for (TopicPartition tp : assignment.topicPartitions()) {
                     tpMemberMap.put(tp, description);

km-common/src/main/java/com/xiaojukeji/know/streaming/km/common/utils/kafka/KSPartialKafkaAdminClient.java

@@ -1338,6 +1338,8 @@ public class KSPartialKafkaAdminClient {
                         if (groupMember.memberAssignment().length > 0) {
                             final Assignment assignment = ConsumerProtocol.deserializeAssignment(ByteBuffer.wrap(groupMember.memberAssignment()));
                             memberBaseAssignment = new KSMemberConsumerAssignment(new HashSet<>(assignment.partitions()));
+                        } else {
+                            memberBaseAssignment = new KSMemberConsumerAssignment(new HashSet<>());
                         }
                     } else {
                         ConnectProtocol.Assignment assignment = null;