public override async Task ExecuteLocalAsync(IMobileServiceLocalStore store, JObject item)
        {
            if (await store.LookupAsync(this.TableName, this.ItemId) != null)
            {
                throw new MobileServiceLocalStoreException("An insert operation on the item is already in the queue.", null);
            }

            await store.UpsertAsync(this.TableName, item, fromServer: false);
        }
        public override async Task ExecuteLocalAsync(IMobileServiceLocalStore store, JObject item)
        {
            if (await store.LookupAsync(this.TableName, this.ItemId) != null)
            {
                throw new MobileServiceLocalStoreException("An insert operation on the item is already in the queue.", null);
            }

            await store.UpsertAsync(this.TableName, item, fromServer : false);
        }
        public override async Task ExecuteLocalAsync(IMobileServiceLocalStore store, JObject item)
        {
            if (await store.LookupAsync(this.TableName, this.ItemId) != null)
            {
                throw new MobileServiceLocalStoreException(Resources.SyncContext_DuplicateInsert, null);
            }

            await store.UpsertAsync(this.TableName, item, fromServer : false);
        }