monitorTarget.appendException(buf, exception);
        assertTrue(buf.toString().contains("Special test exception"));
    }

    // Test multiple appends to the same buffer
    @Test
    public void test_multipleAppends() {
        StringBuilder buf = new StringBuilder();

        monitorTarget.append(buf, "key1", () -> "value1");
        buf.append(",");
        monitorTarget.append(buf, "key2", () -> 123);