return actionClass;
    }

    /**
     * Overrides fillInStackTrace to return null for performance optimization.
     * This prevents stack trace generation for this exception type.
     *
     * @return null to skip stack trace generation
     */
    @Override
    public synchronized Throwable fillInStackTrace() {
        return null;
    }

      // IteratorTester doesn't expect exceptions for hasNext().
      return true;
    }

    @Override
    public E next() {
      ex.fillInStackTrace();
      throw ex;
    }

    @Override
    public void remove() {
      ex.fillInStackTrace();
      throw ex;
    }
  }

      // IteratorTester doesn't expect exceptions for hasNext().
      return true;
    }

    @Override
    public E next() {
      ex.fillInStackTrace();
      throw ex;
    }

    @Override
    public void remove() {
      ex.fillInStackTrace();
      throw ex;
    }
  }

        Throwable[] suppressedExceptions = exception.getSuppressed();
        assertEquals(0, suppressedExceptions.length);
    }

    /**
     * Test fillInStackTrace
     */
    public void test_fillInStackTrace() {
        CrawlerSystemException exception = new CrawlerSystemException("Fill stack trace test");