SONAR suggestion - Synchronize initialization of static fields

Change-Id: I2ddf8220bda49f235ddfc5713174c11a147df354
diff --git a/incubator/net/src/main/java/org/onosproject/incubator/net/dpi/impl/DpiStatisticsManager.java b/incubator/net/src/main/java/org/onosproject/incubator/net/dpi/impl/DpiStatisticsManager.java
index 10f82b4..b49c9cb 100644
--- a/incubator/net/src/main/java/org/onosproject/incubator/net/dpi/impl/DpiStatisticsManager.java
+++ b/incubator/net/src/main/java/org/onosproject/incubator/net/dpi/impl/DpiStatisticsManager.java
@@ -67,7 +67,7 @@
 @Service
 public class DpiStatisticsManager implements DpiStatisticsManagerService {
 
-    private static ServerSocket serverSocket;
+    private ServerSocket serverSocket;
     private static int port = 11990; // socket server listening port
 
     private final Logger log = getLogger(getClass());