fail("Should be able to access private constructor: " + e.getMessage());
        }
    }

    public void test_inheritance() {
        // Verify that SystemUtil extends org.codelibs.core.lang.SystemUtil
        Class<?> superClass = SystemUtil.class.getSuperclass();

            fail("Should throw exception for null property");
        } catch (IllegalArgumentException e) {
            // Expected
        }
    }

    // Test inheritance
    public void test_inheritance() {
        assertTrue(messages instanceof FessLabels);
        assertTrue(messages instanceof org.lastaflute.core.message.UserMessages);
    }

    // Test method chaining