### Question:
AbstractMongoCollection implements MongoCollection<P> { static void validateUpdateQuery(Document update) { Set<String> allModifiedPaths = new LinkedHashSet<>(); for (Object value : update.values()) { Document modification = (Document) value; for (String path : modification.keySet()) { for (String otherPath : allModifiedPaths) { String commonPathPrefix = Utils.getShorterPathIfPrefix(path, otherPath); if (commonPathPrefix != null) { throw new ConflictingUpdateOperatorsException(path, commonPathPrefix); } } allModifiedPaths.add(path); } } } protected  AbstractMongoCollection(MongoDatabase database, String collectionName, CollectionOptions options,
                                      CursorRegistry cursorRegistry); @Override void addDocument(Document document); @Override MongoDatabase getDatabase(); @Override String getCollectionName(); @Override String toString(); @Override void addIndex(Index<P> index); @Override void drop(); @Override void dropIndex(String indexName); @Override Document findAndModify(Document query); @Override QueryResult handleQuery(QueryParameters queryParameters); @Override List<Document> insertDocuments(List<Document> documents, boolean isOrdered); @Override Document handleDistinct(Document query); @Override int deleteDocuments(Document selector, int limit, Oplog oplog); @Override Document updateDocuments(Document selector, Document updateQuery, ArrayFilters arrayFilters,
                                    boolean isMulti, boolean isUpsert, Oplog oplog); @Override List<Index<P>> getIndexes(); @Override int count(Document query, int skip, int limit); @Override Document getStats(); @Override void removeDocument(Document document); @Override Document validate(); @Override void renameTo(MongoDatabase newDatabase, String newCollectionName);  }### Answer:
@Test void testValidateUpdateQuery() throws Exception { AbstractMongoCollection.validateUpdateQuery(new Document()); AbstractMongoCollection.validateUpdateQuery(json("$set: {a: 1, b: 1}")); AbstractMongoCollection.validateUpdateQuery(json("$set: {a: 1, b: 1}, $inc: {c: 1}")); AbstractMongoCollection.validateUpdateQuery(json("$set: {'a.b.c': 1}, $inc: {'a.b.d': 1}")); AbstractMongoCollection.validateUpdateQuery(json("$set: {'a.b.c': 1}, $inc: {'a.c': 1}")); AbstractMongoCollection.validateUpdateQuery(json("$inc: {'a.$.y': 1, 'a.$.x': 1}")); AbstractMongoCollection.validateUpdateQuery(json("$inc: {'a.$.deleted': 1, 'a.$.deletedBy': 1}")); assertThatExceptionOfType(ConflictingUpdateOperatorsException.class) .isThrownBy(() -> AbstractMongoCollection.validateUpdateQuery(json("$set: {a: 1, b: 1}, $inc: {b: 1}"))) .withMessage("[Error 40] Updating the path 'b' would create a conflict at 'b'"); assertThatExceptionOfType(ConflictingUpdateOperatorsException.class) .isThrownBy(() -> AbstractMongoCollection.validateUpdateQuery(json("$set: {'a.b.c': 1}, $inc: {'a.b': 1}"))) .withMessage("[Error 40] Updating the path 'a.b' would create a conflict at 'a.b'"); }