private Set<MessageEnt> messages = new HashSet<MessageEnt>();

@OneToMany (cascade = {CascadeType.PERSIST, CascadeType.MERGE }, mappedBy = "from", fetch=FetchType.EAGER)
@org.hibernate.annotations.Cascade(value = org.hibernate.annotations.CascadeType.SAVE_UPDATE)
public Set<MessageEnt> getMessages() {
   return messages;
}

public void setMessages(Set<MessageEnt> messages) {
   this.messages = messages;
}

public void sendMessage(MessageEnt message){
   if (message == null)
                  throw new IllegalArgumentException("adding null message");
   this.messages.add(message);
   message.setFrom(this);
   message.setTo(message.getTo());
}
   
public void deleteMessage(MessageEnt message){
   if (message == null)
      throw new IllegalArgumentException("removing null message");
   this.messages.remove(message);
   message.setFrom(null);
   message.setTo(null);
}

private UserEnt from;
private UserEnt to;
private String message;
private String subject;

@ManyToOne
@JoinColumn
@NotNull
public UserEnt getFrom() {
                return from;
}

public void setFrom(UserEnt from) {
   this.from = from;
}

@ManyToOne
@JoinColumn
@NotNull
public UserEnt getTo() {
   return to;
}

public void setTo(UserEnt to) {
   this.to = to;
}