ACL exist a bug

[lance12138]

plain_acl.yml 配置文件中如果accessKey命名为admin相关的，且admin参数为true，broker无法启动，且报错：
java.lang.ClassCastException: java.lang.Class cannot be cast to org.apache.rocketmq.acl.AccessValidator
at org.apache.rocketmq.broker.BrokerController.initialAcl(BrokerController.java:503)
at org.apache.rocketmq.broker.BrokerController.initialize(BrokerController.java:470)
at org.apache.rocketmq.broker.BrokerStartup.createBrokerController(BrokerStartup.java:218)
at org.apache.rocketmq.broker.BrokerStartup.main(BrokerStartup.java:58)

报错的配置如下：
`globalWhiteRemoteAddresses:

accounts:

• accessKey: rocketmq1
  secretKey: 12345667778
  whiteRemoteAddress:
  admin: false
  defaultTopicPerm: DENY
  defaultGroupPerm: SUB
  topicPerms:

  • topicB=PUB|SUB
  • topicC=SUB
    groupPerms:
  • groupA=DENY
  • groupB=PUB|SUB
  • groupC=SUB

• accessKey: admin
  secretKey: 12345678
  whiteRemoteAddress: 192.168.1.*
  admin: true
  `

亲测有问题，只要accessKey改掉就可以成功启动

[duhenglucky]

@lance12138 感谢反馈，你能帮忙提个pr改下这个问题吗？

[ph3636]

The accessKey=%s and secretKey=%s cannot be null and length should longer than 6

[ph3636]

@lance12138 @duhenglucky

[zongtanghu]

You can change your acl's accessKey to more than 6 length. @lance12138

[zongtanghu]

And also I will report the useful information for acl config length limite issue.