How to use the generator-jhipster/generators/generator-base.js.prototype function in generator-jhipster

(onResolve) => {
                const conf = onResolve['generator-jhipster'];
                const poly = {};

                // @todo: defensive programming with these properties (hasOwnProperty ? throw ?)

                // jhipsterVar polyfill :
                poly.baseName = conf.baseName;
                poly.packageName = conf.packageName;
                poly.angularAppName = conf.angularAppName || null; // handle an undefined value (JSON properties can't be undefined)
                poly.clientFramework = conf.clientFramework;
                poly.clientPackageManager = conf.clientPackageManager;
                poly.buildTool = conf.buildTool;

                // jhipsterFunc polyfill :
                poly.registerModule = jhipsterModuleSubgenerator.prototype.registerModule;
                poly.updateEntityConfig = jhipsterModuleSubgenerator.prototype.updateEntityConfig;

                // @todo : handle this.options.testMode ?

                return poly;
            },
            (onError) => {

const conf = onResolve['generator-jhipster'];
                const poly = {};

                // @todo: defensive programming with these properties (hasOwnProperty ? throw ?)

                // jhipsterVar polyfill :
                poly.baseName = conf.baseName;
                poly.packageName = conf.packageName;
                poly.angularAppName = conf.angularAppName || null; // handle an undefined value (JSON properties can't be undefined)
                poly.clientFramework = conf.clientFramework;
                poly.clientPackageManager = conf.clientPackageManager;
                poly.buildTool = conf.buildTool;

                // jhipsterFunc polyfill :
                poly.registerModule = jhipsterModuleSubgenerator.prototype.registerModule;
                poly.updateEntityConfig = jhipsterModuleSubgenerator.prototype.updateEntityConfig;

                // @todo : handle this.options.testMode ?

                return poly;
            },
            (onError) => {

(onResolve) => {
                const conf = onResolve['generator-jhipster'];
                const poly = {};

                // jhipsterVar polyfill :
                poly.jhipsterConfig = conf;
                poly.javaDir = `${jhipsterConstants.SERVER_MAIN_SRC_DIR + conf.packageFolder}/`;
                poly.resourceDir = jhipsterConstants.SERVER_MAIN_RES_DIR;
                poly.replaceContent = jhipsterModuleSubgenerator.prototype.replaceContent;
                poly.updateEntityConfig = jhipsterModuleSubgenerator.prototype.updateEntityConfig;

                return poly;
            },
            (onError) => {