fix(3.2): The oneToOne method of the ReactorServerCalls class will cause the request to hang when the result is Mono Empty

[caoyanan666]

What is the purpose of the change

When the return value is Mono Empty, it will cause the request to hang.

Brief changelog

Verifying this change

Checklist

• Make sure there is a GitHub_issue field for the change (usually before you start working on it). Trivial changes like typos do not require a GitHub issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
50.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[caoyanan666]

@AlbumenJ @icodening @EarthChen PTAL

[EarthChen]

LGTM