[Review #4179] MockRequestRecordMapper development.

[Shawn Jim]

Dear Community:

    I`ve to finish MockRequestRecordMapper development of the support API 
document.

    Please help to review/comment. Thanks for your time!

    ISSUE: https://github.com/apache/shenyu/issues/4029.
    PR: https://github.com/apache/shenyu/pull/4179.

Thanks,
Shawn