docs: function fixSourceMapOptions(options) {
    // Rollup <= 0.48 used `sourceMap` in camelcase, so this plugin used
    // this convention at the beginning.
    // Now, the `sourcemap` key should be used, but legacy version should still
    // be able to use the `sourceMap` key.
    const newOptions = _.omitBy(options, (value, key) => (
      key === 'sourceMap'
    ));
  
    // If the old `sourceMap` key is used, set it to `sourcemap` key.
    if (_.hasIn(options, 'sourceMap')) {
      console.warn(`[${PLUGIN_NAME}] sourceMap has been deprecated, please use sourcemap instead.`);
      if (!_.hasIn(newOptions, 'sourcemap')) {
        newOptions.sourcemap = options.sourceMap;
      }
    }
  
    // Validate options.
    validateOptions(newOptions);
  
    return newOptions;
  }