code: public static void writeSymbolToFileMap(Map<Symbol, File> symbolToFileMap, CharSink sink) throws IOException {
      writeSymbolToFileEntries(symbolToFileMap.entrySet(), sink);
    }
docs: Writes a map from symbols to file absolute paths to a file. Each line has a mapping with the key and value
  separated by a single tab.  The file will have a trailing newline.