RM_CHANNELS get npe

[funky-eyes]

• I have searched the issues of this repository and believe that this is not a duplicate.

Ⅰ. Issue Description

rm注册时resourceid未指定,tc二阶段下发shi时由于rm resourceid为null,通过ConcurrentHashMap get(null) 会发生空指针异常,jdk8及以上版本是不允许key为null

Ⅱ. Describe what happened

If there is an exception, please attach the exception trace:

Just paste your stack trace here!

Ⅲ. Describe what you expected to happen

Ⅳ. How to reproduce it (as minimally and precisely as possible)

1. xxx
2. xxx
3. xxx

Minimal yet complete reproducer code (or URL to code):

Ⅴ. Anything else we need to know?

Ⅵ. Environment:

• JDK version(e.g. java -version):
• Seata client/server version:
• Database version:
• OS(e.g. uname -a):
• Others:

[dmego]

plz assgin to me