code: public JsonElement getActualHighWatermark() {
      if (!contains(ConfigurationKeys.WORK_UNIT_STATE_ACTUAL_HIGH_WATER_MARK_KEY)) {
        return null;
      }
      return JSON_PARSER.parse(getProp(ConfigurationKeys.WORK_UNIT_STATE_ACTUAL_HIGH_WATER_MARK_KEY));
    }
docs: Get the actual high {@link Watermark} as a {@link JsonElement}.
  
  @return a {@link JsonElement} representing the actual high {@link Watermark},
  or {@code null} if the actual  high {@link Watermark} is not set.