adding the if condition for only newRoles list iteration.

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/service/GroupManagementProviderServiceImpl.java

@@ -367,7 +367,6 @@ public class GroupManagementProviderServiceImpl implements GroupManagementProvid
     @Override
     public void manageGroupSharing(int groupId, List<String> newRoles)
             throws GroupManagementException, RoleDoesNotExistException {
-        if (newRoles != null) {
             int tenantId = CarbonContext.getThreadLocalCarbonContext().getTenantId();
             UserStoreManager userStoreManager;
             try {
@@ -376,6 +375,7 @@ public class GroupManagementProviderServiceImpl implements GroupManagementProvid
                                 tenantId).getUserStoreManager();
                 List<String> currentUserRoles = getRoles(groupId);
                 GroupManagementDAOFactory.beginTransaction();
+                if (newRoles != null) {
                     for (String role : newRoles) {
                         if (!userStoreManager.isExistingRole(role)) {
                             throw new RoleDoesNotExistException("Role '" + role + "' does not exists in the user store.");
@@ -387,6 +387,7 @@ public class GroupManagementProviderServiceImpl implements GroupManagementProvid
                             groupDAO.addRole(groupId, role, tenantId);
                         }
                     }
+                }
                 for (String role : currentUserRoles) {
                     // Removing old roles from db which are not available in the new roles list.
                     groupDAO.removeRole(groupId, role, tenantId);
@@ -402,9 +403,6 @@ public class GroupManagementProviderServiceImpl implements GroupManagementProvid
             } finally {
                 GroupManagementDAOFactory.closeConnection();
         }
-        } else {
-            throw new GroupManagementException("No roles provided to complete the operation.");
-        }
     }
 
     /**