fix: make Skill abstract, remove redundant ID

src/main/java/cz/fi/muni/pa165/seminar4/group7/secretservice/entity/LanguageSkill.java

@@ -5,20 +5,12 @@ import lombok.Getter;
 import lombok.Setter;
 
 import javax.persistence.Entity;
-import javax.persistence.GeneratedValue;
-import javax.persistence.GenerationType;
-import javax.persistence.Id;
 
 /**
  * @author Juraj Fiala
  */
 @Entity
 public class LanguageSkill extends Skill {
-    @Id
-    @GeneratedValue(strategy = GenerationType.IDENTITY)
-    @Getter
-    @Setter
-    private Long id;
 
     @Getter
     @Setter

src/main/java/cz/fi/muni/pa165/seminar4/group7/secretservice/entity/PerformanceEvaluation.java

@@ -26,7 +26,6 @@ public class PerformanceEvaluation {
     @Setter
     private String evaluation;
 
-    //on a scale of 0 upto 100
     @Getter
     @Setter
     private int rating;

src/main/java/cz/fi/muni/pa165/seminar4/group7/secretservice/entity/Skill.java

@@ -9,7 +9,7 @@ import javax.persistence.*;
  * @author Juraj Fiala
  */
 @Entity
-public class Skill {
+public abstract class Skill {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     @Getter

src/main/java/cz/fi/muni/pa165/seminar4/group7/secretservice/entity/WeaponSkill.java

 package cz.fi.muni.pa165.seminar4.group7.secretservice.entity;
 
-import cz.fi.muni.pa165.seminar4.group7.secretservice.enums.LanguageCode;
 import cz.fi.muni.pa165.seminar4.group7.secretservice.enums.WeaponCategory;
 import lombok.Getter;
 import lombok.Setter;
 
 import javax.persistence.Entity;
-import javax.persistence.GeneratedValue;
-import javax.persistence.GenerationType;
-import javax.persistence.Id;
 
 /**
  * @author Juraj Fiala
  */
 @Entity
 public class WeaponSkill extends Skill {
-    @Id
-    @GeneratedValue(strategy = GenerationType.IDENTITY)
-    @Getter
-    @Setter
-    private Long id;
 
     @Getter
     @Setter