import org.hibernate.*;
import org.hibernate.cfg.*;

public class Test
{
   public static void main(String[] args)
   {
      new Test(args);
   }

   public Test(String[] args)
   {
      AnnotationConfiguration ac = new AnnotationConfiguration();
      ac.configure("hibernate.cfg.xml");

      SessionFactory sf = ac.buildSessionFactory();
      Session s = sf.openSession();
      Transaction t = s.beginTransaction();

      Data d = new Data();
      d.setKey("key");
      d.setValue(new String("value").getBytes());
      s.persist(d);

      // note: the bug does not appear if you do not close & reopen the connection
      t.commit();
      s.close();
      s = sf.openSession();
      t = s.beginTransaction();

      d = (Data)s.get(Data.class, "key");
      System.out.println("value: '" + new String(d.getValue()) + "'");

      s.close();
      sf.close();
   }
}

import javax.persistence.*;

@Entity(access = AccessType.FIELD)
public class Data
{
   @Id
   private String key;

   public String getKey()
   {
      return key;
   }

   public void setKey(String key)
   {
      this.key = key;
   }

   @Lob(type = LobType.BLOB)
   private byte[] value;

   public byte[] getValue()
   {
      return value;
   }

   public void setValue(byte[] value)
   {
      this.value = value;
   }
}

Hibernate: insert into Data (value, key) values (?, ?)
Hibernate: select data0_.key as key0_, data0_.value as value0_0_ from Data data0_ where data0_.key=?
value: 'alue'