public String kv2String(String k, Object v) {
        this.kvs.put(k, v == null ? "" : v);
        return toString();
    }
@Test
    public void testKv2StringShouldPrintMessageAndAllKeyAndValuePairs() {
        String result = logMessage.kv2String("key", "value");
        assertEquals("key=value", result);
    }