Add unit tests to nacos-client module in nacos2.0

[shalk]

Issue Description

This is a sub-issue of [ISSUE #4981]
The nacos-client module coverage rate is just 15%, Could you add more unit tests to nacos-client module?

Anything else we need to know?

To-do list:

• Add unit tests for package com.alibaba.nacos.client.config Add unit tests to package com.alibaba.nacos.client.config in nacos 2.0 #5016
• Add unit tests for package com.alibaba.nacos.client.naming
• Add unit tests for package com.alibaba.nacos.client.monitor
• Add unit tests for package com.alibaba.nacos.client.security
• Add unit tests for package com.alibaba.nacos.client.identify
• Add unit tests for package com.alibaba.nacos.client.logging
• Add unit tests for package com.alibaba.nacos.client.utils

[KomachiSion]

Hi @shalk, Would you like finish this issue?

[shalk]

@KomachiSion I can solve it