How can I use post method data in back end to save many to many relationship data with #JsonIgnore annotation.My joining table is not updating - json

Question

How can I use the data send through post method, and save those data in a many to many relationship? I used #JsonIgnore annotation to stop the recursion.
I have implemented two entities.One is Employee and the other is Skills.In the Employee entity I used #JsonIgnore annotation to avoid the reccursion. But when I inserted the values Employee table got updated but the joining tabled is not updating.
This is my Employee entity class
#Entity
#Table(name = "Employee")
public class Employee implements Serializable{
private static final long serialVersionUID = -3009157732242241606L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long emp_id;
#Column(name = "emp_fname")
private String emp_fname;
#Column(name = "emp_lname")
private String emp_lname;
#Column(name = "emp_email")
private String emp_email;
#Column(name = "emp_dob")
private Date emp_dob;
#ManyToMany(cascade = CascadeType.MERGE)
#JoinTable(name = "emp_skills",
joinColumns = #JoinColumn(name = "emp_id", referencedColumnName = "emp_id"),
inverseJoinColumns = #JoinColumn(name = "s_id",referencedColumnName = "s_id"))
#JsonIgnore
private Set<Skills> skills;
}
This is my Skills class
#Entity
#Table(name = "Skills")
public class Skills implements Serializable {
private static final long serialVersionUID = -3009157732242241606L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long s_id;
#Column(name = "s_name")
private String s_name;
#ManyToMany(mappedBy = "skills")
private Set<Employee> employees;
And this is my controller class method to save data
#RequestMapping("/save")
#PostMapping("/save")
#CrossOrigin
public void createEmployee(#RequestBody Employee employee, BindingResult bindingResult){
Employee emp = new Employee(employee.getEmp_fname(),employee.getEmp_lname(),employee.getEmp_email(),employee.getEmp_dob());
emp.setSkills(employee.getSkills());
empRepository.save(emp);
//empRepository.save(new Employee(employee.getEmp_fname(),employee.getEmp_lname(),employee.getEmp_email(),employee.getEmp_dob()));
}
I want to update both Employee and emp_skills (the joining table) when the save method is triggered.