assertEquals(10000 + "\"longKey\":\"\"".length(), buf.toString().length());
    }

    // Test append with Unicode characters
    @Test
    public void test_append_unicodeCharacters() {
        StringBuilder buf = new StringBuilder();
        Supplier<Object> supplier = () -> "テスト 测试 테스트 🎉";

        monitorTarget.append(buf, "unicodeKey", supplier);