code: function entrySourceMap(entry, callback) {
    const entryData = typeof entry === 'string' ? [entry] : entry;
  
    // get source map
    singleEntrySourceMap(entryData[0], entryData, {}, callback);
  }
docs: Build complete file source map of all entry items from the config.entry.
  
  @method entrySourceMap
  @param {Array|String} entry the entry object
  @param {Function} callback the callback that will return the source map
  @callback {Object} sourceMap the source map object with all files/dirs in entry