[ISSUE #776] make mqadmin usage information more friendly to user(#796)

tools/src/main/java/org/apache/rocketmq/tools/command/topic/UpdateTopicSubCommand.java

@@ -19,6 +19,7 @@ package org.apache.rocketmq.tools.command.topic;
 import java.util.Set;
 import org.apache.commons.cli.CommandLine;
 import org.apache.commons.cli.Option;
+import org.apache.commons.cli.OptionGroup;
 import org.apache.commons.cli.Options;
 import org.apache.rocketmq.common.TopicConfig;
 import org.apache.rocketmq.common.sysflag.TopicSysFlag;
@@ -43,13 +44,16 @@ public class UpdateTopicSubCommand implements SubCommand {
 
     @Override
     public Options buildCommandlineOptions(Options options) {
+        OptionGroup optionGroup = new OptionGroup();
+
         Option opt = new Option("b", "brokerAddr", true, "create topic to which broker");
-        opt.setRequired(false);
-        options.addOption(opt);
+        optionGroup.addOption(opt);
 
         opt = new Option("c", "clusterName", true, "create topic to which cluster");
-        opt.setRequired(false);
-        options.addOption(opt);
+        optionGroup.addOption(opt);
+
+        optionGroup.setRequired(true);
+        options.addOptionGroup(optionGroup);
 
         opt = new Option("t", "topic", true, "topic name");
         opt.setRequired(true);