Fix the problem that the field mapping is not saved

[FinalTarget]

What is the purpose of the change

#311

Brief change log

(for example:)
change init job detail logic.
Fix the problem that the field mapping is not saved

Verifying this change

This change is already covered by existing tests, such as (please describe tests).

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (yes / no) no
• Anything that affects deployment: (yes / no / don't know) no
• The Core framework, i.e., JobManager, Server.: (yes / no) no

Documentation

• Does this pull request introduce a new feature? (yes / no) no
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)

[Davidhua1996]

LGTM.