How to use the @microsoft/sp-build-web.writeManifests function in @microsoft/sp-build-web

additionalConfiguration: (generatedConfiguration) => {
        if (build.getConfig().production) {
            var basePath = build.writeManifests.taskConfig.cdnBasePath;
            if (!basePath.endsWith('/')) {
                basePath += '/';
            }
            generatedConfiguration.output.publicPath = basePath;
        }
        else {
            generatedConfiguration.output.publicPath = "/dist/";
        }
        return generatedConfiguration;
    }
});

additionalConfiguration: (generatedConfiguration) => {
        if (build.getConfig().production) {
            var basePath = build.writeManifests.taskConfig.cdnBasePath;
            if (!basePath.endsWith('/')) {
                basePath += '/';
            }
            generatedConfiguration.output.publicPath = basePath;
        }
        else {
            generatedConfiguration.output.publicPath = "/dist/";
        }
        return generatedConfiguration;
    }
});