assertEquals("\"arrayKey\":[1.5, 2.3, 3.7]", buf.toString());
    }

    // Test append method with empty double array
    @Test
    public void test_append_emptyDoubleArray() {
        StringBuilder buf = new StringBuilder();
        double[] values = {};
        Supplier<Object> supplier = () -> values;

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