public static String getHeartbeatClientIp() {
        String ip = SentinelConfig.getConfig(HEARTBEAT_CLIENT_IP, true);
        if (StringUtil.isBlank(ip)) {
            ip = HostNameUtil.getIp();
        }
        return ip;
    }
@Test
    public void testGetHeartbeatClientIp() {
        String clientIp = "10.10.10.10";
        SentinelConfig.setConfig(TransportConfig.HEARTBEAT_CLIENT_IP, clientIp);
        // Set heartbeat client ip to system property.
        String ip = TransportConfig.getHeartbeatClientIp();

        assertNotNull(ip);
        assertEquals(clientIp, ip);

        // Set no heartbeat client ip.
        SentinelConfig.setConfig(TransportConfig.HEARTBEAT_CLIENT_IP, "");
        assertTrue(StringUtil.isNotEmpty(TransportConfig.getHeartbeatClientIp()));
    }