How to rename JSON properties (@SerializedName) using Gson APIs?

package com.java2novice.json.gson;

import com.google.gson.annotations.SerializedName;

public class Employee {

	@SerializedName("emp_id")
	private int empId;
	
	@SerializedName("emp_name")
	private String name;
	
	private String designation;
	private String department;
	private int salary;
	
	public int getEmpId() {
		return empId;
	}
	public void setEmpId(int empId) {
		this.empId = empId;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getDesignation() {
		return designation;
	}
	public void setDesignation(String designation) {
		this.designation = designation;
	}
	public String getDepartment() {
		return department;
	}
	public void setDepartment(String department) {
		this.department = department;
	}
	public int getSalary() {
		return salary;
	}
	public void setSalary(int salary) {
		this.salary = salary;
	}
}

package com.java2novice.json.gson;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class ObjectToJsonEx {

	public static void main(String a[]){
		
		Employee emp = new Employee();
		emp.setEmpId(1016);
		emp.setName("Nataraj G");
		emp.setSalary(20000);
		emp.setDesignation("Manager");
		emp.setDepartment("Accounts");
		
		Gson gsonObj = new GsonBuilder().setPrettyPrinting().create();
		// converts object to json string
		String jsonStr = gsonObj.toJson(emp);
		System.out.println(jsonStr);
	}
}

{
  "emp_id": 1016,
  "emp_name": "Nataraj G",
  "designation": "Manager",
  "department": "Accounts",
  "salary": 20000
}