Hibernate - вставляются пустые поля

Question

Собственно, hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
        <property name="hibernate.connection.url">jdbc:postgresql://localhost/botweb</property>
        <property name="hibernate.connection.username">postgres</property>
        <property name="hibernate.connection.password">passwordHere</property>
        <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
        <property name="show_sql">true</property>
        <property name="hibernate.hbm2ddl.auto">create-drop</property>
        <mapping class="com.alex4321.botweb.models.Robot" />
        <mapping class="com.alex4321.botweb.models.Visitor" />
        <mapping class="com.alex4321.botweb.models.Conversation" />
        <mapping class="com.alex4321.botweb.models.ConversationItem" />
    </session-factory>
</hibernate-configuration>

Код

@Entity
class BaseEntity {
  ...
}

@Entity
class Visitor {
  public String data;
  ...
}

Session session = AnnotationConfiguration().configure().buildSessionFactory().openSession()
Visitor visitor = Visitor();
visitor.data = "TEST";
session.saveOrUpdate(visitor);

В терминале же

Hibernate: select visitor_.data from Visitor visitor_ where visitor_.data=?
Hibernate: insert into Visitor (data) values (?)