fixed NPE

components/extensions/emqx-extensions/io.entgra.device.mgt.plugins.emqx.exhook/src/main/java/io/entgra/device/mgt/plugins/emqx/exhook/ExServer.java

@@ -44,13 +44,14 @@ import org.wso2.carbon.context.PrivilegedCarbonContext;
 
 import java.io.IOException;
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
 
 public class ExServer {
     private static final Log logger = LogFactory.getLog(ExServer.class.getName());
 
-    private static Map<String, String> accessTokenMap = new HashMap<>();
+    private static Map<String, String> accessTokenMap = new ConcurrentHashMap<>();
-    private static Map<String, String> authorizedScopeMap = new HashMap<>();
+    private static Map<String, String> authorizedScopeMap = new ConcurrentHashMap<>();
     private Server server;
 
     public ExServer() {
@@ -177,6 +178,7 @@ public class ExServer {
             if (request.getResultCode().equals("success")) {
                 String accessToken = accessTokenMap.get(request.getConninfo().getClientid());
                 String scopeString = authorizedScopeMap.get(accessToken);
+                if (!StringUtils.isEmpty(scopeString)) {
                     String[] scopeArray = scopeString.split(" ");
                     String deviceType = null;
                     String deviceId = null;
@@ -199,6 +201,7 @@ public class ExServer {
                         }
                     }
                 }
+            }
             EmptySuccess reply = EmptySuccess.newBuilder().build();
             responseObserver.onNext(reply);
             responseObserver.onCompleted();
@@ -315,12 +318,15 @@ public class ExServer {
                 if (StringUtils.isEmpty(accessToken) || !accessToken.startsWith(request.getClientinfo().getUsername())) {
                     logger.info("Valid access token not found");
                     responseObserver.onError(new Exception("not authorized"));
+                    return;
                 }
 
                 String authorizedScopeList = authorizedScopeMap.get(accessToken);
+                boolean isFound = false;
+                if (!StringUtils.isEmpty(authorizedScopeList)) {
                     String[] scopeArray = authorizedScopeList.split(" ");
                     List<String> scopeList = Arrays.asList(scopeArray);
-                boolean isFound = false;
+
 
                     String tempScope = null;
                     String requestTopic = request.getTopic();
@@ -365,6 +371,7 @@ public class ExServer {
                             }
                         }
                     }
+                }
 
                 if (isFound) {
                     ValuedResponse reply = ValuedResponse.newBuilder()