SONAR suggestion - Synchronize initialization of static fields

Change-Id: I2ddf8220bda49f235ddfc5713174c11a147df354
diff --git a/apps/gluon/src/main/java/org/onosproject/gluon/rsc/GluonServer.java b/apps/gluon/src/main/java/org/onosproject/gluon/rsc/GluonServer.java
index f4f400e..031ba69 100644
--- a/apps/gluon/src/main/java/org/onosproject/gluon/rsc/GluonServer.java
+++ b/apps/gluon/src/main/java/org/onosproject/gluon/rsc/GluonServer.java
@@ -86,10 +86,10 @@
 
 public class GluonServer {
 
-    private static String protonKeyUri;
-    private static String serverUri;
+    private String protonKeyUri;
+    private String serverUri;
 
-    private static CloseableHttpAsyncClient httpClient;
+    private CloseableHttpAsyncClient httpClient;
 
     //store gluon server supported subkeys
     private List<String> subKeys = new LinkedList<>();