Added ProtectedPlayer.java for storing data on protected players. Created an event for players joining and adding the joined player to a list of protected players.

src/main/java/com/micle/loginprotection/setup/Registration.java

@@ -1,10 +1,14 @@
 package com.micle.loginprotection.setup;
 
+import com.micle.loginprotection.events.OnEntityJoinEventHandler;
+import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.eventbus.api.IEventBus;
 import net.minecraftforge.fml.javafmlmod.FMLJavaModLoadingContext;
 
 public class Registration {
     public static void register() {
         IEventBus mod_event_bus = FMLJavaModLoadingContext.get().getModEventBus();
+
+        MinecraftForge.EVENT_BUS.register(new OnEntityJoinEventHandler());
     }
 }