fix: Use incremental numeric id as a key for Tree Grid items (#3046)

* fix: Use incremental numeric id as a key for Tree Grid items

Using Object::toString as an item's key for server-client communication makes item's data visible on the client side, so generated numeric id is used instead.

* Use serializable map

* Use index and depth as an item ID

* fix data provider getId implementation

* use custom unique key provider in tests

Co-authored-by: Soroosh Taefi <taefi.soroosh@gmail.com>
Co-authored-by: Sascha Ißbrücker <sissbruecker@vaadin.com>

(cherry picked from commit 8fe0861)

vaadin-grid-flow-parent/vaadin-grid-flow/src/main/java/com/vaadin/flow/component/treegrid/TreeGrid.java

@@ -18,10 +18,13 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.concurrent.atomic.AtomicLong;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -143,8 +146,12 @@ public UpdateQueueData getUpdateQueueData() {
         }
     }
 
-    private final ValueProvider<T, String> defaultUniqueKeyProvider = item -> getDataProvider()
-            .getId(item).toString();
+    private final AtomicLong uniqueKeyCounter = new AtomicLong(0);
+    private final Map<Object, Long> objectUniqueKeyMap = new HashMap<>();
+
+    ValueProvider<T, String> defaultUniqueKeyProvider = item -> String.valueOf(
+            objectUniqueKeyMap.computeIfAbsent(getDataProvider().getId(item),
+                    key -> uniqueKeyCounter.getAndIncrement()));
 
     private Registration dataProviderRegistration;
 

vaadin-grid-flow-parent/vaadin-grid-flow/src/test/java/com/vaadin/flow/component/grid/TreeGridTest.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2000-2022 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.vaadin.flow.component.grid;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.vaadin.flow.component.treegrid.TreeGrid;
+import com.vaadin.flow.function.ValueProvider;
+
+public class TreeGridTest {
+
+    @Test
+    public void defaultUniqueKeyProvider_usesIncrementalLongId() {
+        Item item1 = new Item("sensitive data 1");
+        Item item2 = new Item("sensitive data 2");
+
+        UniqueKeyTreeGrid grid = new UniqueKeyTreeGrid();
+        String key1 = grid.getUniqueKeyProvider().apply(item1);
+        Assert.assertEquals("0", key1);
+
+        String key2 = grid.getUniqueKeyProvider().apply(item2);
+        Assert.assertEquals("1", key2);
+
+        key1 = grid.getUniqueKeyProvider().apply(item1);
+        Assert.assertEquals("0", key1);
+    }
+
+    private static class UniqueKeyTreeGrid extends TreeGrid<Item> {
+        @Override
+        public ValueProvider<Item, String> getUniqueKeyProvider() {
+            return super.getUniqueKeyProvider();
+        }
+    }
+
+    private static class Item {
+        private final String sensitiveData;
+
+        public Item(String sensitiveData) {
+            this.sensitiveData = sensitiveData;
+        }
+
+        public String getSensitiveData() {
+            return sensitiveData;
+        }
+    }
+
+}