feature:add User-Agent:polaris for healthyCheck api.

spring-cloud-starter-tencent-polaris-discovery/src/main/java/com/tencent/cloud/polaris/registry/PolarisServiceRegistry.java

@@ -18,6 +18,8 @@
 
 package com.tencent.cloud.polaris.registry;
 
+import java.util.HashMap;
+import java.util.Map;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 
@@ -40,6 +42,7 @@ import org.slf4j.LoggerFactory;
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.cloud.client.serviceregistry.ServiceRegistry;
+import org.springframework.http.HttpHeaders;
 
 import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.springframework.util.ReflectionUtils.rethrowRuntimeException;
@@ -200,7 +203,9 @@ public class PolarisServiceRegistry implements ServiceRegistry<PolarisRegistrati
 				String healthCheckUrl = String.format("http://%s:%s%s", heartbeatRequest.getHost(),
 						heartbeatRequest.getPort(), healthCheckEndpoint);
 
-				if (!OkHttpUtil.get(healthCheckUrl, null)) {
+				Map<String, String> headers = new HashMap<>(1);
+				headers.put(HttpHeaders.USER_AGENT, "polaris");
+				if (!OkHttpUtil.get(healthCheckUrl, headers)) {
 					LOGGER.error("backend service health check failed. health check endpoint = {}",
 							healthCheckEndpoint);
 					return;

spring-cloud-starter-tencent-polaris-discovery/src/main/java/com/tencent/cloud/polaris/util/OkHttpUtil.java

@@ -27,6 +27,7 @@ import java.util.concurrent.TimeUnit;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.StringUtils;
 
 /**
@@ -60,6 +61,9 @@ public final class OkHttpUtil {
 			conn.setRequestMethod("GET");
 			conn.setConnectTimeout((int) TimeUnit.SECONDS.toMillis(2));
 			conn.setReadTimeout((int) TimeUnit.SECONDS.toMillis(2));
+			if (!CollectionUtils.isEmpty(headers)) {
+				headers.forEach(conn::setRequestProperty);
+			}
 			BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
 			StringBuffer buffer = new StringBuffer();
 			String str;

spring-cloud-starter-tencent-polaris-discovery/src/test/java/com/tencent/cloud/polaris/util/OkHttpUtilTest.java

@@ -26,6 +26,7 @@ import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.web.server.LocalServerPort;
 import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestHeader;
 import org.springframework.web.bind.annotation.RestController;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -53,8 +54,8 @@ public class OkHttpUtilTest {
 	@RestController
 	static class TestApplication {
 		@GetMapping("/test")
-		public String test() {
-			return "test";
+		public String test(@RequestHeader("key") String key) {
+			return key;
 		}
 	}
 }