Facing a duplicate constraint error in Spring Boot

I have a employee Form where in the employee table I need to capture datas from three different table like designation, country, state from dropdown but when I am inserting the data for the first time data is captured i.e. insert query is working properly but from second time it is showing duplicate constraint for designationId,countryId,stateId.

As after running this query SHOW CREATE TABLE tbl_employee I can See that the table is created with Unique Keys for designationId, countryId, stateId these fields. Don't know how..

CREATE TABLE `tbl_employee` (
  `employee_id` BIGINT NOT NULL AUTO_INCREMENT,
  `aadhar` VARCHAR(255) DEFAULT NULL,
  `address_line1` VARCHAR(255) DEFAULT NULL,
  `address_line2` VARCHAR(255) DEFAULT NULL,
  `city` VARCHAR(255) DEFAULT NULL,
  `dateof_birth` VARCHAR(255) DEFAULT NULL,
  `dateof_joining` VARCHAR(255) DEFAULT NULL,
  `email` VARCHAR(255) DEFAULT NULL,
  `name` VARCHAR(255) DEFAULT NULL,
  `pan` VARCHAR(255) DEFAULT NULL,
  `password` VARCHAR(255) DEFAULT NULL,
  `zip` VARCHAR(255) DEFAULT NULL,
  `country_id` BIGINT DEFAULT NULL,
  `designation_id` BIGINT DEFAULT NULL,
  `state_id` BIGINT DEFAULT NULL,
  PRIMARY KEY (`employee_id`),
  **UNIQUE KEY** `UK_ku8jubtc7x8evqgglfhafudl4` (`country_id`),
  **UNIQUE KEY** `UK_2d8ftabh5yvknmnufwqllhyi0` (`designation_id`),
  **UNIQUE KEY** `UK_nj8cpqu4dp6qqiix9g8xd4qj2` (`state_id`),
  CONSTRAINT `FKl3gotmdj4q5ns5we62h71usr7` FOREIGN KEY (`designation_id`) REFERENCES `tbl_designation` (`id`),
  CONSTRAINT `FKlei86ulei19r01bm15a8qb2ls` FOREIGN KEY (`country_id`) REFERENCES `tbl_country` (`country_id`),
  CONSTRAINT `FKrp2jdmscq9awnqumwkowp8hfe` FOREIGN KEY (`state_id`) REFERENCES `tbl_state` (`state_id`)
) ENGINE=INNODB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

Sharing the Entity Class

Employee.java
@Entity
@Table(name = "tbl_employee")
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
public class EmployeeEntity {

	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	Long employeeId;

	@OneToOne(cascade = CascadeType.ALL)
	@JoinColumn(name = "designationId")
	private Designation designationInfo;

	@OneToOne(cascade = CascadeType.ALL)
	@JoinColumn(name = "countryId")
	private Country country;

	@OneToOne(cascade = CascadeType.ALL)
	@JoinColumn(name = "stateId")
	private State state;
}

Country.java
@Entity(name = "tbl_country")
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
public class Country {

	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	Long countryId;
	String country_name;
	
	 @OneToMany(cascade = CascadeType.ALL)
	 @JoinColumn(name = "fk_country_id",referencedColumnName = "countryId")
	private List<State> states;
}


State.java
@Entity(name = "tbl_state")
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
public class State {

	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	Long stateId;
	String state_name;

	 @ManyToOne
	 @JoinColumn(name = "fk_country_id")
	 private Country country;
}

Just Changing the Relation the problem is resolved

  @ManyToOne(cascade = CascadeType.ALL ,fetch = FetchType.LAZY)
	@JoinColumn(name = "designationId" , unique = false)
	private Designation designationInfo;

	@ManyToOne(cascade = CascadeType.ALL ,fetch = FetchType.LAZY)
	@JoinColumn(name = "countryId", unique = false)
	private Country country;

	@ManyToOne(cascade = CascadeType.ALL ,fetch = FetchType.LAZY)
	@JoinColumn(name = "stateId", unique = false)
	private State state;