Property access of the returned object throws ODatabaseException: Database not set in current thread - orientdb

Question

I'm using orientdb-object-2.1.9 and trying to setup a basic repository to save and find objects.
But when accessing any property of the returned object from the database, it throws an ODatabaseException, that Database is not set in current thread.
Here is a failing test, showing my usage of the API.
import javax.persistence.Id;
import javax.persistence.Version;
import com.orientechnologies.orient.core.db.OPartitionedDatabasePool;
import com.orientechnologies.orient.object.db.OObjectDatabaseTx;
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
public class ObjectDatabaseTest {
private MyObjectAuthorRepository repository;
#Before
public void setUp() {
repository = new MyObjectAuthorRepository();
}
#After
public void tearDown() {
repository.close();
}
#Test
public void testAuthor() {
Author savedAuthor = repository.saveAuthor(new Author("Author Name"));
// a detached object also fails when accessing the property
// Assert.assertEquals("Author Name", savedAuthor.getAuthorName());
Author author = repository.findAuthor();
Assert.assertEquals("Author Name", author.getAuthorName());
}
class MyObjectAuthorRepository {
private final OPartitionedDatabasePool pool;
public MyObjectAuthorRepository() {
pool = new OPartitionedDatabasePool("memory:test", "admin", "admin");
pool.setAutoCreate(true);
try (OObjectDatabaseTx db = new OObjectDatabaseTx(pool.acquire())) {
db.setAutomaticSchemaGeneration(true);
db.getEntityManager().registerEntityClass(Author.class);
}
}
private Author saveAuthor(Author author) {
OObjectDatabaseTx db = new OObjectDatabaseTx(pool.acquire());
try {
db.begin();
Author savedAuthor = db.save(author);
db.commit();
return db.detach(savedAuthor);
} catch (Exception ex) {
db.rollback();
throw ex;
} finally {
db.close();
}
}
public Author findAuthor() {
try (OObjectDatabaseTx db = new OObjectDatabaseTx(pool.acquire())) {
return db.browseClass(Author.class).next();
}
}
public void close() {
pool.close();
}
}
#javax.persistence.Entity
public class Author {
#Id
private String id;
#Version
private Long version;
private String authorName;
public Author() {
}
public Author(String authorName) {
this.authorName = authorName;
}
public String getId() {
return id;
}
public Long getVersion() {
return version;
}
public String getAuthorName() {
return authorName;
}
public void setAuthorName(String authorName) {
this.authorName = authorName;
}
}
}
Please let me know, if the API should be used in a different way or if any other configuration I'm missing here above. It'll be really helpful. Thanks.