fix return JSONObject instead of null, for issue #3419

[yanxutao89]

What this PR does / why we need it?

fix return JSONObject instead of null

Summary of your change

Please indicate you've done the following:

• Made sure tests are passing and test coverage is added if needed.
• Made sure commit message follow the rule of Conventional Commits specification.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed.