fix(3.2): triple reactor call throws "Too many response for unary method" exception

[caoyanan666]

What is the purpose of the change

When triple response write successfully, it always throws "java.lang.IllegalStateException: Too many response for unary method"。

Mono subscribe method third parameter will always calls when it is completed, so i fix it!

Brief changelog

Verifying this change

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[icodening]

LGTM