code: @Deprecated
    public File getClassesDir() {
      final FileCollection col = getClassesDirs();
      return (col == null) ? null : col.getSingleFile();
    }
docs: Directory with the class files to check.
  Defaults to current sourseSet's output directory (Gradle 2/3 only).
  @deprecated use {@link #getClassesDirs()} instead. If there are more than one
  {@code classesDir} set by {@link #setClassesDirs(FileCollection)}, this getter may
  throw an exception!