how to generate object parameter in openapi-generator-cli

I have been using openapi-generator-cli to generate typescript. The function output is something like

const someFunc = (a?, b?, c?, d?) => {
    // ...
};

but I would like it to look like

const someFunc = ({a, b, c, d}) => {
    // ...
};

I have been looking through the docs but now find any solutions. Also, I don't want to change the spec.yaml format since my backend dev will not do it.