code: public void start() {
          addSymbolsFromSettings();
          File rep = new File(context.getSettings().getTargetPath());
          rep.mkdirs();
          try {
              java4cppLog = new FileWriter(new File(getPath(JAVA4CPP_LOG)));
          } catch (IOException e) {
              System.err.println("Can't create log file: " + e.getMessage());
          }
          try {
              File[] existings = rep.listFiles(new SourceFilter());
              if (existings != null) {
                  oldFiles = new ArrayList<File>(Arrays.asList(existings));
              }
              java4cppHash = new File(getPath(JAVA4CPP_HASH));
              BufferedInputStream in = new BufferedInputStream(new FileInputStream(java4cppHash));
              oldHashes.load(in);
              in.close();
              java4cppHash.delete();
          } catch (IOException e) {
              logInfo("no java4cpp.hash file, regenerating all files");
          }
      }
docs: Called before starting generating proxies files. Create the
  {@code java4cpp.log} log file, and manage the {@code clean} and
  {@code useHash} settings.