monitorTarget.append(buf, "emptyArrayKey", supplier);
        assertEquals("\"emptyArrayKey\":[]", buf.toString());
    }

    // Test append method with String value
    @Test
    public void test_append_stringValue() {
        StringBuilder buf = new StringBuilder();
        Supplier<Object> supplier = () -> "test string";

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