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/data/ProtectedPlayer.java

@@ -0,0 +1,35 @@
+package com.micle.loginprotection.data;
+
+import java.util.UUID;
+
+public class ProtectedPlayer {
+    private final UUID player_uuid;
+    private int grace_period;
+    private boolean is_loading;
+
+    public ProtectedPlayer(UUID player_uuid) {
+        this.player_uuid = player_uuid;
+        this.grace_period = 200;
+        this.is_loading = true;
+    }
+
+    public UUID getPlayerUUID() {
+        return this.player_uuid;
+    }
+
+    public int getGracePeriod() {
+        return this.grace_period;
+    }
+
+    public void setGracePeriod(int new_grace_period) {
+        this.grace_period = new_grace_period;
+    }
+
+    public boolean isLoading() {
+        return this.is_loading;
+    }
+
+    public void setLoading(boolean new_loading) {
+        this.is_loading = new_loading;
+    }
+}