Slight cleanup and better support for server reloads

common/src/main/java/me/lucko/luckperms/data/Datastore.java

@@ -48,6 +48,7 @@ public abstract class Datastore {
         These methods will block the thread that they're ran on.
      */
     public abstract void init(DatastoreConfiguration configuration);
+    public abstract void shutdown();
     public abstract boolean loadOrCreateUser(UUID uuid, String username);
     public abstract boolean loadUser(UUID uuid);
     public abstract boolean saveUser(User user);

common/src/main/java/me/lucko/luckperms/data/HikariDatastore.java

@@ -104,6 +104,13 @@ public class HikariDatastore extends Datastore {
         setupTables();
     }
 
+    @Override
+    public void shutdown() {
+        if (hikari != null) {
+            hikari.shutdown();
+        }
+    }
+
     @Override
     public boolean loadUser(UUID uuid) {
         User user = plugin.getUserManager().makeUser(uuid);