Fixing potential memory leak

Common/src/main/java/dev/brighten/antivpn/api/VPNExecutor.java

@@ -1,6 +1,7 @@
 package dev.brighten.antivpn.api;
 
 import dev.brighten.antivpn.AntiVPN;
+import dev.brighten.antivpn.utils.EvictingMap;
 import dev.brighten.antivpn.utils.VPNResponse;
 import dev.brighten.antivpn.utils.json.JSONException;
 import lombok.Getter;
@@ -15,7 +16,7 @@ import java.util.function.Consumer;
 public abstract class VPNExecutor {
     public static ExecutorService threadExecutor = Executors.newSingleThreadExecutor();
 
-    public static final Map<String, VPNResponse> responseCache = new HashMap<>();
+    public static final Map<String, VPNResponse> responseCache = new EvictingMap<>(5000);
     @Getter
     private final Set<UUID> whitelisted = Collections.synchronizedSet(new HashSet<>());
     @Getter

Common/src/main/java/dev/brighten/antivpn/utils/EvictingMap.java

@@ -0,0 +1,19 @@
+package dev.brighten.antivpn.utils;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+@RequiredArgsConstructor
+public class EvictingMap<K, V> extends LinkedHashMap<K, V> {
+
+    @Getter
+    private final int size;
+
+    @Override
+    protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
+        return size() >= size;
+    }
+}