Simplify Monster skills with Set instead of List

Doable now with MobSkillId records

src/main/java/server/life/LifeFactory.java

@@ -188,7 +188,7 @@ public class LifeFactory {
         Data monsterSkillInfoData = monsterInfoData.getChildByPath("skill");
         if (monsterSkillInfoData != null) {
             int i = 0;
-            List<MobSkillId> skills = new ArrayList<>();
+            Set<MobSkillId> skills = new HashSet<>();
             while (monsterSkillInfoData.getChildByPath(Integer.toString(i)) != null) {
                 int skillId = DataTool.getInt(i + "/skill", monsterSkillInfoData, 0);
                 int skillLv = DataTool.getInt(i + "/level", monsterSkillInfoData, 0);

src/main/java/server/life/Monster.java

@@ -1426,7 +1426,7 @@ public class Monster extends AbstractLoadedLife {
         return map.getAggroCoordinator();
     }
 
-    public List<MobSkillId> getSkills() {
+    public Set<MobSkillId> getSkills() {
         return stats.getSkills();
     }
 
@@ -1434,19 +1434,6 @@ public class Monster extends AbstractLoadedLife {
         return stats.hasSkill(skillId, level);
     }
 
-    public int getSkillPos(int skillId, int level) {
-        int pos = 0;
-        for (MobSkillId ms : this.getSkills()) {
-            if (ms.type().getId() == skillId && ms.level() == level) {
-                return pos;
-            }
-
-            pos++;
-        }
-
-        return -1;
-    }
-
     public boolean canUseSkill(MobSkill toUse, boolean apply) {
         if (toUse == null || isBuffed(MonsterStatus.SEAL_SKILL)) {
             return false;
@@ -1600,8 +1587,20 @@ public class Monster extends AbstractLoadedLife {
         }
     }
 
-    public int getNoSkills() {
-        return this.stats.getNoSkills();
+    public boolean hasAnySkill() {
+        return this.stats.getNoSkills() > 0;
+    }
+
+    public MobSkillId getRandomSkill() {
+        Set<MobSkillId> skills = stats.getSkills();
+        if (skills.size() == 0) {
+            return null;
+        }
+        // There is no simple way of getting a random element from a Set. Have to make do with this.
+        return skills.stream()
+                .skip(Randomizer.nextInt(skills.size()))
+                .findAny()
+                .orElse(null);
     }
 
     public boolean isFirstAttack() {

src/main/java/server/life/MonsterStats.java

@@ -41,7 +41,7 @@ public class MonsterStats {
     public Map<Element, ElementalEffectiveness> resistance = new HashMap<>();
     public List<Integer> revives = Collections.emptyList();
     public byte tagColor, tagBgColor;
-    public List<MobSkillId> skills = new ArrayList<>();
+    public Set<MobSkillId> skills = new HashSet<>();
     public Pair<Integer, Integer> cool = null;
     public BanishInfo banish = null;
     public List<loseItem> loseItem = null;
@@ -190,17 +190,12 @@ public class MonsterStats {
         this.tagBgColor = (byte) tagBgColor;
     }
 
-    public void setSkills(List<MobSkillId> skills) {
-        for (int i = this.skills.size(); i < skills.size(); i++) {
-            this.skills.add(null);
-        }
-        for (int i = 0; i < skills.size(); i++) {
-            this.skills.set(i, skills.get(i));
-        }
+    public void setSkills(Set<MobSkillId> skills) {
+        this.skills = skills;
     }
 
-    public List<MobSkillId> getSkills() {
-        return Collections.unmodifiableList(this.skills);
+    public Set<MobSkillId> getSkills() {
+        return Collections.unmodifiableSet(this.skills);
     }
 
     public int getNoSkills() {