code: function OptimizeCssnanoPlugin(options) {
    this.options = Object.assign({
      sourceMap: false,
      cssnanoOptions: {
        preset: 'default',
      },
    }, options);
  
    if (this.options.sourceMap) {
      this.options.sourceMap = Object.assign(
        {inline: false},
        this.options.sourceMap || {});
    }
  }
docs: Optimize cssnano plugin
  
  @param {Object} options