Enable overriding the client in DiscoveryManager (#1417)

eureka-client/src/main/java/com/netflix/discovery/DiscoveryManager.java

@@ -42,6 +42,7 @@
 public class DiscoveryManager {
     private static final Logger logger = LoggerFactory.getLogger(DiscoveryManager.class);
     private DiscoveryClient discoveryClient;
+    private EurekaClient clientOverride;
 
     private EurekaInstanceConfig eurekaInstanceConfig;
     private EurekaClientConfig eurekaClientConfig;
@@ -58,6 +59,10 @@ public void setDiscoveryClient(DiscoveryClient discoveryClient) {
         this.discoveryClient = discoveryClient;
     }
 
+    public void setClientOverride(EurekaClient eurekaClient) {
+        this.clientOverride = eurekaClient;
+    }
+
     public void setEurekaClientConfig(EurekaClientConfig eurekaClientConfig) {
         this.eurekaClientConfig = eurekaClientConfig;
     }
@@ -107,7 +112,7 @@ public void shutdownComponent() {
     }
 
     public LookupService getLookupService() {
-        return discoveryClient;
+        return getEurekaClient();
     }
 
     /**
@@ -127,6 +132,9 @@ public DiscoveryClient getDiscoveryClient() {
      * @return the client that is used to talk to eureka.
      */
     public EurekaClient getEurekaClient() {
+        if (clientOverride != null) {
+            return clientOverride;
+        }
         return discoveryClient;
     }