final String json = coordinatorHelper.toJson(map);
        assertNotNull(json);
        assertTrue(json.contains("\"type\":\"heartbeat\""));
        assertTrue(json.contains("\"instanceId\":\"test-instance\""));
        assertTrue(json.contains("\"createdTime\":1000"));
    }

    @Test
    public void test_toJson_emptyMap() {
        final String json = coordinatorHelper.toJson(Map.of());
        assertEquals("{}", json);