JPA...tabela associativa como chave PK....?Duvida

CREATE TABLE `employer_employee` (
  `EMPER_ID` int(11) NOT NULL,
  `EMPEE_ID` int(11) NOT NULL,
  KEY `FKDC9B93B29245299A` (`EMPEE_ID`),
  KEY `FKDC9B93B2924B127A` (`EMPER_ID`),
  CONSTRAINT `FKDC9B93B2924B127A` FOREIGN KEY (`EMPER_ID`) REFERENCES `employer` (`EMPER_ID`),
  CONSTRAINT `FKDC9B93B29245299A` FOREIGN KEY (`EMPEE_ID`) REFERENCES `employee` (`EMPEE_ID`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

[/code}


minha duvida queria que cada campo fosse PK  pois estou vendo acima que somente
está KEY ....

no MYSQL é assim mesmo ???????????????????????????????????


se alguém puder me ajudar agradeceria...



abs


[code]
import java.io.Serializable;
import java.util.Collection;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.Table;


@Entity
@Table
public class Employer implements Serializable {

    @Id
    @Column(name="EMPER_ID")
    private int id;
    @ManyToMany(
        targetEntity=Employee.class,
        cascade={CascadeType.PERSIST, CascadeType.MERGE}
    )
    @JoinTable(
        name="EMPLOYER_EMPLOYEE",
        joinColumns=@JoinColumn(name="EMPER_ID"),
        inverseJoinColumns=@JoinColumn(name="EMPEE_ID")
    )
    
    private Collection<Employee> employees;
    
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public Collection<Employee> getEmployees() {
		return employees;
	}
	public void setEmployees(Collection<Employee> employees) {
		this.employees = employees;
	}
    
   
    
}
-----
@Entity
@Table
public class Employee implements Serializable {
	@Id
	@Column(name="EMPEE_ID")
	private int id;
    @ManyToMany(
        cascade = {CascadeType.PERSIST, CascadeType.MERGE},
        mappedBy = "employees",
        targetEntity = Employer.class
    )
    private Collection<Employer>  employers;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public Collection<Employer> getEmployers() {
		return employers;
	}
	public void setEmployers(Collection<Employer> employers) {
		this.employers = employers;
	} 
    
    
}