public String getListenKeyMd5(String connectionId, String groupKey) {
        Map<String, String> groupKeyContexts = connectionIdContext.get(connectionId);
        return groupKeyContexts == null ? null : groupKeyContexts.get(groupKey);
    }
@Test
    void testGetListenKeyMd5() {
        configChangeListenContext.addListen("groupKey", "md5", "connectionId");
        String listenKeyMd5 = configChangeListenContext.getListenKeyMd5("connectionId", "groupKey");
        assertEquals("md5", listenKeyMd5);
    }