Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

If an array with unique items exists in the schema the generated code does not compile.
Because the data is stored in a QSet and output.append is caleld which is not present instead output.insert should be called

openapi-generator version

5.4.0.

OpenAPI declaration file content or url

Attached as file.

Generation Details

(Ubuntu 20.0)
java -jar openapi-generator-cli-5.4.0.jar generate -i unique_petstore.json -g cpp-qt-client -o unique_petstore

Steps to reproduce

Generate client via generator for cpp qt
cmake -S . -B \build
cmake --build \build

Following error should appear:

/home/thi/Projects/Github/oai-cpp-qt-client/unique_petstore/client/OAIPetsApi.cpp:388:16: error: ‘class QSet<OpenAPI::OAIPet>’ has no member named ‘append’  
  388 |         output.append(val);  
      |                ^~~~~~  
make[2]: *** [client/CMakeFiles/client.dir/build.make:105: client/CMakeFiles/client.dir/OAIPetsApi.cpp.o] Error 1  
make[2]: Leaving directory '/home/thi/Projects/Github/oai-cpp-qt-client/unique_petstore/build'  
make[1]: *** [CMakeFiles/Makefile2:98: client/CMakeFiles/client.dir/all] Error 2  

Suggest a fix

Coming soon

unique_petstore.txt