opendaylight/md-sal/sal-dom-broker/src/test/java/org/opendaylight/controller/md/sal/dom/broker/impl/DOMDataTreeListenerTest.java

   1 /*
   2  * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.controller.md.sal.dom.broker.impl;
   9
  10 import static org.junit.Assert.assertEquals;
  11 import static org.junit.Assert.assertFalse;
  12 import static org.junit.Assert.assertNotNull;
  13 import static org.junit.Assert.assertTrue;
  14 import static org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType.CONFIGURATION;
  15 import static org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType.OPERATIONAL;
  16
  17 import com.google.common.collect.ImmutableMap;
  18 import com.google.common.util.concurrent.ForwardingExecutorService;
  19 import com.google.common.util.concurrent.ListeningExecutorService;
  20 import com.google.common.util.concurrent.MoreExecutors;
  21 import java.util.ArrayList;
  22 import java.util.Collection;
  23 import java.util.List;
  24 import java.util.concurrent.CountDownLatch;
  25 import java.util.concurrent.ExecutionException;
  26 import java.util.concurrent.ExecutorService;
  27 import java.util.concurrent.Executors;
  28 import java.util.concurrent.TimeUnit;
  29 import org.junit.After;
  30 import org.junit.Before;
  31 import org.junit.Test;
  32 import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
  33 import org.opendaylight.controller.md.sal.common.api.data.TransactionCommitDeadlockException;
  34 import org.opendaylight.controller.md.sal.dom.api.DOMDataBrokerExtension;
  35 import org.opendaylight.controller.md.sal.dom.api.DOMDataTreeChangeListener;
  36 import org.opendaylight.controller.md.sal.dom.api.DOMDataTreeChangeService;
  37 import org.opendaylight.controller.md.sal.dom.api.DOMDataTreeIdentifier;
  38 import org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction;
  39 import org.opendaylight.controller.md.sal.dom.store.impl.InMemoryDOMDataStore;
  40 import org.opendaylight.controller.md.sal.dom.store.impl.TestModel;
  41 import org.opendaylight.controller.sal.core.spi.data.DOMStore;
  42 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  43 import org.opendaylight.yangtools.util.concurrent.DeadlockDetectingListeningExecutorService;
  44 import org.opendaylight.yangtools.util.concurrent.SpecialExecutors;
  45 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  46 import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
  47 import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
  48 import org.opendaylight.yangtools.yang.data.api.schema.MapNode;
  49 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  50 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
  51 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateNode;
  52 import org.opendaylight.yangtools.yang.data.api.schema.tree.ModificationType;
  53 import org.opendaylight.yangtools.yang.data.impl.schema.Builders;
  54 import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNodes;
  55 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  56
  57 @Deprecated
  58 public class DOMDataTreeListenerTest {
  59
  60     private SchemaContext schemaContext;
  61     private AbstractDOMDataBroker domBroker;
  62     private ListeningExecutorService executor;
  63     private ExecutorService futureExecutor;
  64     private CommitExecutorService commitExecutor;
  65
  66     private static final DataContainerChild<?, ?> OUTER_LIST = ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME)
  67             .withChild(ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1)).build();
  68
  69     private static final DataContainerChild<?, ?> OUTER_LIST_2 = ImmutableNodes
  70             .mapNodeBuilder(TestModel.OUTER_LIST_QNAME)
  71             .withChild(ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 2)).build();
  72
  73     private static final NormalizedNode<?, ?> TEST_CONTAINER = Builders.containerBuilder()
  74             .withNodeIdentifier(new YangInstanceIdentifier.NodeIdentifier(TestModel.TEST_QNAME)).withChild(OUTER_LIST)
  75             .build();
  76
  77     private static final NormalizedNode<?, ?> TEST_CONTAINER_2 = Builders.containerBuilder()
  78             .withNodeIdentifier(new YangInstanceIdentifier.NodeIdentifier(TestModel.TEST_QNAME)).withChild(OUTER_LIST_2)
  79             .build();
  80
  81     private static DOMDataTreeIdentifier ROOT_DATA_TREE_ID = new DOMDataTreeIdentifier(
  82             LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH);
  83
  84     private static DOMDataTreeIdentifier OUTER_LIST_DATA_TREE_ID = new DOMDataTreeIdentifier(
  85             LogicalDatastoreType.CONFIGURATION, TestModel.OUTER_LIST_PATH);
  86
  87     @Before
  88     public void setupStore() {
  89         InMemoryDOMDataStore operStore = new InMemoryDOMDataStore("OPER", MoreExecutors.newDirectExecutorService());
  90         InMemoryDOMDataStore configStore = new InMemoryDOMDataStore("CFG", MoreExecutors.newDirectExecutorService());
  91         schemaContext = TestModel.createTestContext();
  92
  93         operStore.onGlobalContextUpdated(schemaContext);
  94         configStore.onGlobalContextUpdated(schemaContext);
  95
  96         final ImmutableMap<LogicalDatastoreType, DOMStore> stores = ImmutableMap.<LogicalDatastoreType,
  97                 DOMStore>builder() //
  98                 .put(CONFIGURATION, configStore) //
  99                 .put(OPERATIONAL, operStore) //
 100                 .build();
 101
 102         commitExecutor = new CommitExecutorService(Executors.newSingleThreadExecutor());
 103         futureExecutor = SpecialExecutors.newBlockingBoundedCachedThreadPool(1, 5, "FCB",
 104                 DOMDataTreeListenerTest.class);
 105         executor = new DeadlockDetectingListeningExecutorService(commitExecutor,
 106                                                                  TransactionCommitDeadlockException
 107                                                                          .DEADLOCK_EXCEPTION_SUPPLIER,
 108                                                                  futureExecutor);
 109         domBroker = new SerializedDOMDataBroker(stores, executor);
 110     }
 111
 112     @After
 113     public void tearDown() {
 114         if (executor != null) {
 115             executor.shutdownNow();
 116         }
 117
 118         if (futureExecutor != null) {
 119             futureExecutor.shutdownNow();
 120         }
 121     }
 122
 123     @Test
 124     public void writeContainerEmptyTreeTest() throws InterruptedException {
 125         CountDownLatch latch = new CountDownLatch(1);
 126
 127         DOMDataTreeChangeService dataTreeChangeService = getDOMDataTreeChangeService();
 128         assertNotNull("DOMDataTreeChangeService not found, cannot continue with test!", dataTreeChangeService);
 129
 130         final TestDataTreeListener listener = new TestDataTreeListener(latch);
 131         final ListenerRegistration<TestDataTreeListener> listenerReg = dataTreeChangeService
 132                 .registerDataTreeChangeListener(ROOT_DATA_TREE_ID, listener);
 133
 134         final DOMDataWriteTransaction writeTx = domBroker.newWriteOnlyTransaction();
 135         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH, TEST_CONTAINER);
 136         writeTx.commit();
 137
 138         latch.await(5, TimeUnit.SECONDS);
 139
 140         assertEquals(1, listener.getReceivedChanges().size());
 141         final Collection<DataTreeCandidate> changes = listener.getReceivedChanges().get(0);
 142         assertEquals(1, changes.size());
 143
 144         DataTreeCandidate candidate = changes.iterator().next();
 145         assertNotNull(candidate);
 146         DataTreeCandidateNode candidateRoot = candidate.getRootNode();
 147         checkChange(null, TEST_CONTAINER, ModificationType.WRITE, candidateRoot);
 148         listenerReg.close();
 149     }
 150
 151     @Test
 152     public void replaceContainerContainerInTreeTest() throws InterruptedException, ExecutionException {
 153         final CountDownLatch latch = new CountDownLatch(2);
 154
 155         DOMDataTreeChangeService dataTreeChangeService = getDOMDataTreeChangeService();
 156         assertNotNull("DOMDataTreeChangeService not found, cannot continue with test!", dataTreeChangeService);
 157
 158         DOMDataWriteTransaction writeTx = domBroker.newWriteOnlyTransaction();
 159         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH, TEST_CONTAINER);
 160         writeTx.commit().get();
 161
 162         final TestDataTreeListener listener = new TestDataTreeListener(latch);
 163         final ListenerRegistration<TestDataTreeListener> listenerReg = dataTreeChangeService
 164                 .registerDataTreeChangeListener(ROOT_DATA_TREE_ID, listener);
 165         writeTx = domBroker.newWriteOnlyTransaction();
 166         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH, TEST_CONTAINER_2);
 167         writeTx.commit();
 168
 169         latch.await(5, TimeUnit.SECONDS);
 170
 171         assertEquals(2, listener.getReceivedChanges().size());
 172         Collection<DataTreeCandidate> changes = listener.getReceivedChanges().get(0);
 173         assertEquals(1, changes.size());
 174
 175         DataTreeCandidate candidate = changes.iterator().next();
 176         assertNotNull(candidate);
 177         DataTreeCandidateNode candidateRoot = candidate.getRootNode();
 178         checkChange(null, TEST_CONTAINER, ModificationType.WRITE, candidateRoot);
 179
 180         changes = listener.getReceivedChanges().get(1);
 181         assertEquals(1, changes.size());
 182
 183         candidate = changes.iterator().next();
 184         assertNotNull(candidate);
 185         candidateRoot = candidate.getRootNode();
 186         checkChange(TEST_CONTAINER, TEST_CONTAINER_2, ModificationType.WRITE, candidateRoot);
 187         listenerReg.close();
 188     }
 189
 190     @Test
 191     public void deleteContainerContainerInTreeTest() throws InterruptedException, ExecutionException {
 192         final CountDownLatch latch = new CountDownLatch(2);
 193
 194         DOMDataTreeChangeService dataTreeChangeService = getDOMDataTreeChangeService();
 195         assertNotNull("DOMDataTreeChangeService not found, cannot continue with test!", dataTreeChangeService);
 196
 197         DOMDataWriteTransaction writeTx = domBroker.newWriteOnlyTransaction();
 198         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH, TEST_CONTAINER);
 199         writeTx.commit().get();
 200
 201         final TestDataTreeListener listener = new TestDataTreeListener(latch);
 202         final ListenerRegistration<TestDataTreeListener> listenerReg = dataTreeChangeService
 203                 .registerDataTreeChangeListener(ROOT_DATA_TREE_ID, listener);
 204
 205         writeTx = domBroker.newWriteOnlyTransaction();
 206         writeTx.delete(LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH);
 207         writeTx.commit();
 208
 209         latch.await(5, TimeUnit.SECONDS);
 210
 211         assertEquals(2, listener.getReceivedChanges().size());
 212         Collection<DataTreeCandidate> changes = listener.getReceivedChanges().get(0);
 213         assertEquals(1, changes.size());
 214
 215         DataTreeCandidate candidate = changes.iterator().next();
 216         assertNotNull(candidate);
 217         DataTreeCandidateNode candidateRoot = candidate.getRootNode();
 218         checkChange(null, TEST_CONTAINER, ModificationType.WRITE, candidateRoot);
 219
 220         changes = listener.getReceivedChanges().get(1);
 221         assertEquals(1, changes.size());
 222
 223         candidate = changes.iterator().next();
 224         assertNotNull(candidate);
 225         candidateRoot = candidate.getRootNode();
 226         checkChange(TEST_CONTAINER, null, ModificationType.DELETE, candidateRoot);
 227         listenerReg.close();
 228     }
 229
 230     @Test
 231     public void replaceChildListContainerInTreeTest() throws InterruptedException, ExecutionException {
 232         final CountDownLatch latch = new CountDownLatch(2);
 233
 234         DOMDataTreeChangeService dataTreeChangeService = getDOMDataTreeChangeService();
 235         assertNotNull("DOMDataTreeChangeService not found, cannot continue with test!", dataTreeChangeService);
 236
 237         DOMDataWriteTransaction writeTx = domBroker.newWriteOnlyTransaction();
 238         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH, TEST_CONTAINER);
 239         writeTx.commit().get();
 240
 241         final TestDataTreeListener listener = new TestDataTreeListener(latch);
 242         final ListenerRegistration<TestDataTreeListener> listenerReg = dataTreeChangeService
 243                 .registerDataTreeChangeListener(ROOT_DATA_TREE_ID, listener);
 244
 245         writeTx = domBroker.newWriteOnlyTransaction();
 246         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.OUTER_LIST_PATH, OUTER_LIST_2);
 247         writeTx.commit();
 248
 249         latch.await(5, TimeUnit.SECONDS);
 250
 251         assertEquals(2, listener.getReceivedChanges().size());
 252         Collection<DataTreeCandidate> changes = listener.getReceivedChanges().get(0);
 253         assertEquals(1, changes.size());
 254
 255         DataTreeCandidate candidate = changes.iterator().next();
 256         assertNotNull(candidate);
 257         DataTreeCandidateNode candidateRoot = candidate.getRootNode();
 258         checkChange(null, TEST_CONTAINER, ModificationType.WRITE, candidateRoot);
 259
 260         changes = listener.getReceivedChanges().get(1);
 261         assertEquals(1, changes.size());
 262
 263         candidate = changes.iterator().next();
 264         assertNotNull(candidate);
 265         candidateRoot = candidate.getRootNode();
 266         checkChange(TEST_CONTAINER, TEST_CONTAINER_2, ModificationType.SUBTREE_MODIFIED, candidateRoot);
 267         final DataTreeCandidateNode modifiedChild = candidateRoot
 268                 .getModifiedChild(new YangInstanceIdentifier.NodeIdentifier(TestModel.OUTER_LIST_QNAME)).get();
 269         checkChange(OUTER_LIST, OUTER_LIST_2, ModificationType.WRITE, modifiedChild);
 270         listenerReg.close();
 271     }
 272
 273     @Test
 274     public void rootModificationChildListenerTest() throws InterruptedException, ExecutionException {
 275         final CountDownLatch latch = new CountDownLatch(2);
 276
 277         DOMDataTreeChangeService dataTreeChangeService = getDOMDataTreeChangeService();
 278         assertNotNull("DOMDataTreeChangeService not found, cannot continue with test!", dataTreeChangeService);
 279
 280         DOMDataWriteTransaction writeTx = domBroker.newWriteOnlyTransaction();
 281         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH, TEST_CONTAINER);
 282         writeTx.commit().get();
 283
 284         final TestDataTreeListener listener = new TestDataTreeListener(latch);
 285         final ListenerRegistration<TestDataTreeListener> listenerReg = dataTreeChangeService
 286                 .registerDataTreeChangeListener(OUTER_LIST_DATA_TREE_ID, listener);
 287
 288         writeTx = domBroker.newWriteOnlyTransaction();
 289         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH, TEST_CONTAINER_2);
 290         writeTx.commit().get();
 291
 292         latch.await(1, TimeUnit.SECONDS);
 293
 294         assertEquals(2, listener.getReceivedChanges().size());
 295         Collection<DataTreeCandidate> changes = listener.getReceivedChanges().get(0);
 296         assertEquals(1, changes.size());
 297
 298         DataTreeCandidate candidate = changes.iterator().next();
 299         assertNotNull(candidate);
 300         DataTreeCandidateNode candidateRoot = candidate.getRootNode();
 301         checkChange(null, OUTER_LIST, ModificationType.WRITE, candidateRoot);
 302
 303         changes = listener.getReceivedChanges().get(1);
 304         assertEquals(1, changes.size());
 305
 306         candidate = changes.iterator().next();
 307         assertNotNull(candidate);
 308         candidateRoot = candidate.getRootNode();
 309         checkChange(OUTER_LIST, OUTER_LIST_2, ModificationType.WRITE, candidateRoot);
 310         listenerReg.close();
 311     }
 312
 313     @Test
 314     public void listEntryChangeNonRootRegistrationTest() throws InterruptedException, ExecutionException {
 315         final CountDownLatch latch = new CountDownLatch(2);
 316
 317         DOMDataTreeChangeService dataTreeChangeService = getDOMDataTreeChangeService();
 318         assertNotNull("DOMDataTreeChangeService not found, cannot continue with test!", dataTreeChangeService);
 319
 320         DOMDataWriteTransaction writeTx = domBroker.newWriteOnlyTransaction();
 321         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.TEST_PATH, TEST_CONTAINER);
 322         writeTx.commit().get();
 323
 324         final TestDataTreeListener listener = new TestDataTreeListener(latch);
 325         final ListenerRegistration<TestDataTreeListener> listenerReg = dataTreeChangeService
 326                 .registerDataTreeChangeListener(OUTER_LIST_DATA_TREE_ID, listener);
 327
 328         final YangInstanceIdentifier.NodeIdentifierWithPredicates outerListEntryId1
 329                 = YangInstanceIdentifier.NodeIdentifierWithPredicates.of(TestModel.OUTER_LIST_QNAME,
 330                                                                           TestModel.ID_QNAME, 1);
 331         final YangInstanceIdentifier.NodeIdentifierWithPredicates outerListEntryId2
 332                 = YangInstanceIdentifier.NodeIdentifierWithPredicates.of(TestModel.OUTER_LIST_QNAME,
 333                                                                           TestModel.ID_QNAME, 2);
 334         final YangInstanceIdentifier.NodeIdentifierWithPredicates outerListEntryId3
 335                 = YangInstanceIdentifier.NodeIdentifierWithPredicates.of(TestModel.OUTER_LIST_QNAME,
 336                                                                           TestModel.ID_QNAME, 3);
 337
 338         final MapEntryNode outerListEntry1 = ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 1);
 339         final MapEntryNode outerListEntry2 = ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 2);
 340         final MapEntryNode outerListEntry3 = ImmutableNodes.mapEntry(TestModel.OUTER_LIST_QNAME, TestModel.ID_QNAME, 3);
 341
 342         final MapNode listAfter = ImmutableNodes.mapNodeBuilder(TestModel.OUTER_LIST_QNAME).withChild(outerListEntry2)
 343                 .withChild(outerListEntry3).build();
 344
 345         writeTx = domBroker.newWriteOnlyTransaction();
 346         writeTx.delete(LogicalDatastoreType.CONFIGURATION, TestModel.OUTER_LIST_PATH.node(outerListEntryId1));
 347         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.OUTER_LIST_PATH.node(outerListEntryId2),
 348                     outerListEntry2);
 349         writeTx.put(LogicalDatastoreType.CONFIGURATION, TestModel.OUTER_LIST_PATH.node(outerListEntryId3),
 350                     outerListEntry3);
 351         writeTx.commit();
 352
 353         latch.await(5, TimeUnit.SECONDS);
 354
 355         assertEquals(2, listener.getReceivedChanges().size());
 356         Collection<DataTreeCandidate> changes = listener.getReceivedChanges().get(0);
 357         assertEquals(1, changes.size());
 358
 359         DataTreeCandidate candidate = changes.iterator().next();
 360         assertNotNull(candidate);
 361         DataTreeCandidateNode candidateRoot = candidate.getRootNode();
 362         checkChange(null, OUTER_LIST, ModificationType.WRITE, candidateRoot);
 363
 364         changes = listener.getReceivedChanges().get(1);
 365         assertEquals(1, changes.size());
 366
 367         candidate = changes.iterator().next();
 368         assertNotNull(candidate);
 369         candidateRoot = candidate.getRootNode();
 370         checkChange(OUTER_LIST, listAfter, ModificationType.SUBTREE_MODIFIED, candidateRoot);
 371         final DataTreeCandidateNode entry1Canditate = candidateRoot.getModifiedChild(outerListEntryId1).get();
 372         checkChange(outerListEntry1, null, ModificationType.DELETE, entry1Canditate);
 373         final DataTreeCandidateNode entry2Canditate = candidateRoot.getModifiedChild(outerListEntryId2).get();
 374         checkChange(null, outerListEntry2, ModificationType.WRITE, entry2Canditate);
 375         final DataTreeCandidateNode entry3Canditate = candidateRoot.getModifiedChild(outerListEntryId3).get();
 376         checkChange(null, outerListEntry3, ModificationType.WRITE, entry3Canditate);
 377         listenerReg.close();
 378     }
 379
 380     private static void checkChange(final NormalizedNode<?, ?> expectedBefore, final NormalizedNode<?, ?> expectedAfter,
 381                                     final ModificationType expectedMod, final DataTreeCandidateNode candidateNode) {
 382         if (expectedBefore != null) {
 383             assertTrue(candidateNode.getDataBefore().isPresent());
 384             assertEquals(expectedBefore, candidateNode.getDataBefore().get());
 385         } else {
 386             assertFalse(candidateNode.getDataBefore().isPresent());
 387         }
 388
 389         if (expectedAfter != null) {
 390             assertTrue(candidateNode.getDataAfter().isPresent());
 391             assertEquals(expectedAfter, candidateNode.getDataAfter().get());
 392         } else {
 393             assertFalse(candidateNode.getDataAfter().isPresent());
 394         }
 395
 396         assertEquals(expectedMod, candidateNode.getModificationType());
 397     }
 398
 399     private DOMDataTreeChangeService getDOMDataTreeChangeService() {
 400         final DOMDataBrokerExtension extension = domBroker.getSupportedExtensions().get(DOMDataTreeChangeService.class);
 401         if (extension == null) {
 402             return null;
 403         }
 404         DOMDataTreeChangeService dataTreeChangeService = null;
 405         if (extension instanceof DOMDataTreeChangeService) {
 406             dataTreeChangeService = (DOMDataTreeChangeService) extension;
 407         }
 408         return dataTreeChangeService;
 409     }
 410
 411
 412     static class CommitExecutorService extends ForwardingExecutorService {
 413
 414         ExecutorService delegate;
 415
 416         CommitExecutorService(final ExecutorService delegate) {
 417             this.delegate = delegate;
 418         }
 419
 420         @Override
 421         protected ExecutorService delegate() {
 422             return delegate;
 423         }
 424     }
 425
 426     static class TestDataTreeListener implements DOMDataTreeChangeListener {
 427
 428         private final List<Collection<DataTreeCandidate>> receivedChanges = new ArrayList<>();
 429         private final CountDownLatch latch;
 430
 431         TestDataTreeListener(final CountDownLatch latch) {
 432             this.latch = latch;
 433         }
 434
 435         @Override
 436         public void onDataTreeChanged(final Collection<DataTreeCandidate> changes) {
 437             receivedChanges.add(changes);
 438             latch.countDown();
 439         }
 440
 441         public List<Collection<DataTreeCandidate>> getReceivedChanges() {
 442             return receivedChanges;
 443         }
 444     }
 445 }