code: private void initOutputDir(File outputDir) {
  
          if (!outputDir.exists()) {
              if (!outputDir.mkdirs()) {
                  throw new IllegalArgumentException("Output Directory "+outputDir+" could not be created");
              }
          }
          if (!outputDir.isDirectory() || (!outputDir.canWrite())) {
              throw new IllegalArgumentException("Output Directory "+outputDir+" is not a directory or cannot be written to.");
          }
      }
docs: Set up and validate the creation of the specified output directory