when ManyToOne is part of the primaryKey

[Ajay Aggarwal]

I have 2 simple tables, user and contacts. A user may have many
contacts. So I use OneToMany and ManyToOne in corresponding entities:

Class User {
   @Id 
   long userId;
   String username;

   @OneToMany (mappedBy="user")
   List <UserContact> contacts;
}

Class UserContact {
   String contactPhone;
   String contactName;

  @ManyToOne
  User user;
}

Now I am struggling with the UserContact entity:
Q1. How do I specify that it's PRIMARY KEY=user+contactPhone? 
Q2. How do I specify a UNIQUE constraint on a combination of
user+contactName?

Thanks.