public void putMetricsValue(String key, String value) {
        this.loaderMetrics.put(key, value);
    }
@Test
    void testSerialization() throws JsonProcessingException {
        ServerLoaderInfoResponse response = new ServerLoaderInfoResponse();
        response.putMetricsValue("test", "testValue");
        String actual = mapper.writeValueAsString(response);
        System.out.println(actual);
        assertTrue(actual.contains("\"loaderMetrics\":{\"test\":\"testValue\"}"));
    }