### Question:
ObjectVersionManager { public boolean isEmpty() { return versionGraph.isEmpty(); } ObjectVersionManager(Class<O> clazz);  ObjectVersionManager(ObjectSerializer<O> serializer, boolean useSchemaFilter); ObjectVersionManager<O, M> init(); ObjectVersionManager<O, M> init(Iterable<ObjectVersion<M>> versions); ObjectVersionManager<O, M> init(VersionGraph<PropertyPath, Object, M> versionGraph); ManagedObjectVersionBuilder<M> versionBuilder(O object); MergeObject<O, M> mergeBranches(String... branches); MergeObject<O, M> mergeBranches(Collection<String> branches); MergeObject<O, M> mergeRevisions(Collection<Revision> revisions); VersionNode<PropertyPath, Object, M> commit(Version<PropertyPath, Object, M> version); VersionGraph<PropertyPath, Object, M> getVersionGraph(); Set<Revision> getHeads(); VersionNode<PropertyPath, Object, M> getVersionNode(Revision revision); Set<String> getBranches(); Schema<ValueType> getSchema(); boolean isEmpty();  }### Answer:
@Test public void is_empty() { assertThat(versionManager.isEmpty(), equalTo(true)); }