monitorTarget.append(buf, "emptyKey", supplier);
        assertEquals("\"emptyKey\":\"\"", buf.toString());
    }

    // Test append with very long string
    @Test
    public void test_append_veryLongString() {
        StringBuilder buf = new StringBuilder();
        String longString = "a".repeat(10000);
        Supplier<Object> supplier = () -> longString;

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