docs: public static Field getOptionalField(Class<?> clazz, String fieldName)
    {
      try {
        Field field = clazz.getDeclaredField(fieldName);
        field.setAccessible(true);
        return field;
      }
      catch(NoSuchFieldException expectable) {}
      catch(SecurityException e) {
        throw new BugError(e);
      }
      return null;
    }