Project.java

@Entity
public class Project {

  @Id
  private long id;
  ...
  @OneToMany
  private List<ProjectAssociation> employees;
  ...
  // Add an employee to the project.
  // Create an association object for the relationship and set its' data.publicvoid addEmployee(Employee employee, boolean teamLead) {
    ProjectAssociation association =new ProjectAssociation();
    association.setEmployee(employee);
    association.setProject(this);
    association.setEmployeeId(employee.getId());
    association.setProjectId(this.getId());
    association.setIsTeamLead(teamLead);
 
    employees.add(association);
  }
}