Use org.reflections to get all subclass of MineClassImpl in order to avoid the declaration inside the MineClassFactory

build.gradle

@@ -1,5 +1,16 @@
 import org.apache.tools.ant.filters.ReplaceTokens
+import com.github.jengelman.gradle.plugins.shadow.tasks.ConfigureShadowRelocation
 
+buildscript {
+    repositories {
+        jcenter()
+    }
+    dependencies {
+        classpath 'com.github.jengelman.gradle.plugins:shadow:5.1.0'
+    }
+}
+
+apply plugin: 'com.github.johnrengelman.shadow'
 apply plugin: 'java'
 
 group = 'net.babamod'
@@ -22,6 +33,7 @@ repositories {
 
 dependencies {
     compileOnly 'org.spigotmc:spigot-api:1.16.3-R0.1-SNAPSHOT'
+    compile group: 'org.reflections', name: 'reflections', version: '0.9.10'
 }
 
 processResources {
@@ -29,3 +41,15 @@ processResources {
         filter ReplaceTokens, tokens: [version: version]
     }
 }
+
+shadowJar {
+    archiveBaseName.set('mineclass')
+    archiveClassifier.set('')
+    archiveVersion.set('')
+}
+
+task relocateShadowJar(type: ConfigureShadowRelocation) {
+    target = tasks.shadowJar
+}
+
+tasks.shadowJar.dependsOn tasks.relocateShadowJar

src/main/java/net/babamod/mineclass/Mineclass.java

@@ -5,13 +5,12 @@ import net.babamod.mineclass.commands.CommandClass;
 import net.babamod.mineclass.listeners.MineClassListeners;
 import org.bukkit.Bukkit;
 import org.bukkit.command.PluginCommand;
-import org.bukkit.event.Listener;
 import org.bukkit.plugin.java.JavaPlugin;
 
 import java.util.ArrayList;
 import java.util.List;
 
-public final class Mineclass extends JavaPlugin implements Listener {
+public final class Mineclass extends JavaPlugin {
 
   @Override
   public void onEnable() {

src/main/java/net/babamod/mineclass/classes/BeastMasterClass.java

@@ -11,6 +11,7 @@ import java.util.*;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+@SuppressWarnings("unused")
 public class BeastMasterClass extends MineClassImpl {
 
   private static final Set<Material> forbiddenItems =

src/main/java/net/babamod/mineclass/classes/DwarfClass.java

@@ -10,6 +10,7 @@ import java.util.*;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+@SuppressWarnings("unused")
 public class DwarfClass extends MineClassImpl {
 
   private final Set<Material> forbiddenItems =

src/main/java/net/babamod/mineclass/classes/ElfClass.java

@@ -10,6 +10,7 @@ import java.util.*;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+@SuppressWarnings("unused")
 public class ElfClass extends MineClassImpl {
 
   private static final Set<Material> forbiddenItems =

src/main/java/net/babamod/mineclass/classes/EnderElfClass.java

@@ -13,6 +13,7 @@ import java.util.*;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+@SuppressWarnings("unused")
 public class EnderElfClass extends MineClassImpl {
 
   private static final Set<Material> forbiddenItems =

src/main/java/net/babamod/mineclass/classes/FireDwarfClass.java

@@ -10,6 +10,7 @@ import java.util.*;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+@SuppressWarnings("unused")
 public class FireDwarfClass extends MineClassImpl {
 
   private static final Set<Material> forbiddenItems =

src/main/java/net/babamod/mineclass/classes/MineClassFactory.java

@@ -1,11 +1,14 @@
 package net.babamod.mineclass.classes;
 
+import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.meta.ItemMeta;
 import org.bukkit.potion.PotionEffect;
+import org.reflections.Reflections;
 
 import java.util.*;
+import java.util.logging.Level;
 
 public class MineClassFactory {
   /** Instance unique pré-initialisée */
@@ -16,11 +19,15 @@ public class MineClassFactory {
   /** Constructeur privé */
   private MineClassFactory() {
     availableClasses = new HashMap<>();
-    availableClasses.put("dwarf", new DwarfClass());
-    availableClasses.put("elf", new ElfClass());
-    availableClasses.put("fire_dwarf", new FireDwarfClass());
-    availableClasses.put("ender_elf", new EnderElfClass());
-    availableClasses.put("beast_master", new BeastMasterClass());
+    // Reflecting all MineClass classes and instantiates them with there codes
+    for (Class<? extends MineClassImpl> aClass : new Reflections().getSubTypesOf(MineClassImpl.class)) {
+      try {
+        MineClass mineClass = aClass.newInstance();
+        availableClasses.put(mineClass.getCode(), mineClass);
+      } catch (InstantiationException | IllegalAccessException e) {
+        Bukkit.getLogger().log(Level.WARNING, e.getMessage());
+      }
+    }
   }
 
   /** Point d'accès pour l'instance unique du singleton */