It's a working a bit.

But no permissions are calculated for online players.

src/main/java/ru/simsonic/rscPermissions/Bukkit/BukkitCommands.java

@@ -256,12 +256,7 @@ public class BukkitCommands
 				{
 					case "permissions":
 						list.add("{MAGENTA}Permission list for {_YL}" + player.getName());
-						final PermissionAttachment pa = rscp.permissionManager.attachments.get(player);
-						if(pa == null)
-							break;
-						final Map<String, Boolean> pv = pa.getPermissions();
-						if(pv == null)
-							break;
+						final Map<String, Boolean> pv = rscp.permissionManager.listPlayerPermissions(player);
 						final ArrayList<String> sorted_keys = new ArrayList<>(pv.keySet());
 						Collections.sort(sorted_keys);
 						for(String perm : sorted_keys)

src/main/java/ru/simsonic/rscPermissions/Bukkit/BukkitMaintenance.java

@@ -11,19 +11,23 @@ import ru.simsonic.rscUtilityLibrary.TextProcessing.GenericChatCodes;
 
 public class BukkitMaintenance implements Listener
 {
-	private final BukkitPluginMain plugin;
+	private final BukkitPluginMain rscp;
 	public BukkitMaintenance(BukkitPluginMain rscp)
 	{
-		this.plugin = rscp;
+		this.rscp = rscp;
+	}
+	public void onEnable()
+	{
+		rscp.getServer().getPluginManager().registerEvents(this, rscp);
 	}
 	@org.bukkit.event.EventHandler
 	public void onServerPing(ServerListPingEvent event)
 	{
-		if(plugin.settings.isInMaintenance())
+		if(rscp.settings.isInMaintenance())
 		{
 			String motd = "Server is under maintenance";
-			motd = plugin.getConfig().getString("language.maintenance.locked.default.motd", motd);
-			motd = plugin.getConfig().getString("language.maintenance.locked." + plugin.settings.getMaintenanceMode() + ".motd", motd);
+			motd = rscp.getConfig().getString("language.maintenance.locked.default.motd", motd);
+			motd = rscp.getConfig().getString("language.maintenance.locked." + rscp.settings.getMaintenanceMode() + ".motd", motd);
 			motd = GenericChatCodes.processStringStatic(motd);
 			if(!"".equals(motd))
 				event.setMotd(motd);
@@ -32,18 +36,18 @@ public class BukkitMaintenance implements Listener
 	@org.bukkit.event.EventHandler
 	public void onAsyncPlayerPreLogin(AsyncPlayerPreLoginEvent event)
 	{
-		if("".equals(plugin.settings.getMaintenanceMode()))
+		if("".equals(rscp.settings.getMaintenanceMode()))
 		{
 			event.allow();
 			return;
 		}
 		final String permissionAll = "rscp.maintenance.*";
-		final String permission_mm = "rscp.maintenance." + (plugin.settings.getMaintenanceMode());
+		final String permission_mm = "rscp.maintenance." + (rscp.settings.getMaintenanceMode());
 		final HashMap<String, Boolean> permissions = new HashMap<>();
 		try
 		{
 			final String name = event.getName();
-			plugin.internalCache.resolvePlayer(name, plugin.getServer().getServerId());
+			rscp.internalCache.resolvePlayer(name, rscp.getServer().getServerId());
 			// permissions.putAll(plugin.cache.mapPermissions.get(name));
 		} catch(RuntimeException ex) {
 		}
@@ -51,7 +55,7 @@ public class BukkitMaintenance implements Listener
 		{
 			final UUID uuid = event.getUniqueId();
 			final String userFriendlyUniqueId = uuid.toString().replace("-", "").toLowerCase();
-			plugin.internalCache.resolvePlayer(userFriendlyUniqueId, plugin.getServer().getServerId());
+			rscp.internalCache.resolvePlayer(userFriendlyUniqueId, rscp.getServer().getServerId());
 			// permissions.putAll(plugin.cache.mapPermissions.get(userFriendlyUniqueId));
 		} catch(RuntimeException | NoSuchMethodError ex) {
 		}
@@ -62,17 +66,17 @@ public class BukkitMaintenance implements Listener
 				return;
 			}
 		String kickMsg = "{_YL}Server is in maintenance mode\nPlease try to connect later...";
-		kickMsg = plugin.getConfig().getString("language.maintenance.locked.default.motd", kickMsg);
-		kickMsg = plugin.getConfig().getString("language.maintenance.locked." + plugin.settings.getMaintenanceMode() + ".motd", kickMsg);
+		kickMsg = rscp.getConfig().getString("language.maintenance.locked.default.motd", kickMsg);
+		kickMsg = rscp.getConfig().getString("language.maintenance.locked." + rscp.settings.getMaintenanceMode() + ".motd", kickMsg);
 		kickMsg = GenericChatCodes.processStringStatic(kickMsg);
 		event.disallow(AsyncPlayerPreLoginEvent.Result.KICK_WHITELIST, kickMsg);
 	}
 	public void setMaintenanceMode(String mMode)
 	{
-		plugin.settings.setMaintenanceMode(mMode);
-		if(!plugin.settings.isInMaintenance())
+		rscp.settings.setMaintenanceMode(mMode);
+		if(!rscp.settings.isInMaintenance())
 			return;
-		plugin.getServer().getScheduler().scheduleSyncDelayedTask(plugin, new Runnable()
+		rscp.getServer().getScheduler().scheduleSyncDelayedTask(rscp, new Runnable()
 		{
 			@Override
 			public void run()
@@ -82,11 +86,11 @@ public class BukkitMaintenance implements Listener
 					{
 						if(player.hasPermission("rscp.maintenance.*"))
 							continue;
-						if(player.hasPermission("rscp.maintenance." + plugin.settings.getMaintenanceMode()))
+						if(player.hasPermission("rscp.maintenance." + rscp.settings.getMaintenanceMode()))
 							continue;
 						String kick = "{_YL}Server is going into maintenance mode";
-						kick = plugin.getConfig().getString("language.maintenance.locked.default.kick", kick);
-						kick = plugin.getConfig().getString("language.maintenance.locked." + plugin.settings.getMaintenanceMode() + ".kick", kick);
+						kick = rscp.getConfig().getString("language.maintenance.locked.default.kick", kick);
+						kick = rscp.getConfig().getString("language.maintenance.locked." + rscp.settings.getMaintenanceMode() + ".kick", kick);
 						kick = GenericChatCodes.processStringStatic(kick);
 						player.kickPlayer(kick);
 					}

src/main/java/ru/simsonic/rscPermissions/Bukkit/BukkitPermissionManager.java

@@ -1,6 +1,9 @@
 package ru.simsonic.rscPermissions.Bukkit;
+import java.net.InetSocketAddress;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.LinkedBlockingQueue;
 import org.bukkit.entity.Player;
@@ -19,11 +22,11 @@ public class BukkitPermissionManager extends RestartableThread
 		this.rscp = plugin;
 	}
 	private final LinkedBlockingQueue<Player> updateQueue = new LinkedBlockingQueue<>();
-	private final HashMap<Player, String> prefixes = new HashMap<>();
-	private final HashMap<Player, String> suffixes = new HashMap<>();
+	private final HashMap<Player, PermissionAttachment> attachments = new HashMap<>();
 	private final HashMap<Player, RowPermission[]> persistentPermissions = new HashMap<>();
 	private final HashMap<Player, RowPermission[]> transientPermissions = new HashMap<>();
-	public  final HashMap<Player, PermissionAttachment> attachments = new HashMap<>();
+	private final HashMap<Player, String> prefixes = new HashMap<>();
+	private final HashMap<Player, String> suffixes = new HashMap<>();
 	public void recalculateOnlinePlayersSync()
 	{
 		try
@@ -58,6 +61,22 @@ public class BukkitPermissionManager extends RestartableThread
 		} catch(InterruptedException ex) {
 		}
 	}
+	public Map<String, Boolean> listPlayerPermissions(Player player)
+	{
+		final PermissionAttachment attachment = rscp.permissionManager.attachments.get(player);
+		if(attachment != null)
+			return attachment.getPermissions();
+		return Collections.EMPTY_MAP;
+	}
+	public void removePlayer(Player player)
+	{
+		updateQueue.remove(player);
+		attachments.remove(player);
+		prefixes.remove(player);
+		suffixes.remove(player);
+		persistentPermissions.remove(player);
+		transientPermissions.remove(player);
+	}
 	@Override
 	public void run()
 	{
@@ -143,7 +162,9 @@ public class BukkitPermissionManager extends RestartableThread
 			// minecraft <= 1.7.x
 		}
 		// IP address of a Player can be used as entity name too
-		result.add(player.getAddress().getAddress().getHostAddress());
+		InetSocketAddress socketAddress = player.getAddress();
+		if(socketAddress != null)
+			result.add(socketAddress.getAddress().getHostAddress());
 		return result.toArray(new String[result.size()]);
 	}
 }

src/main/java/ru/simsonic/rscPermissions/Bukkit/PlayerEventsListener.java

@@ -45,13 +45,13 @@ public class PlayerEventsListener implements Listener
 	@EventHandler
 	public void onPlayerKick(PlayerKickEvent event)
 	{
-		rscp.permissionManager.attachments.remove(event.getPlayer());
+		rscp.permissionManager.removePlayer(event.getPlayer());
 		rscp.regionListProvider.removePlayer(event.getPlayer());
 	}
 	@EventHandler
 	public void onPlayerQuit(PlayerQuitEvent event)
 	{
-		rscp.permissionManager.attachments.remove(event.getPlayer());
+		rscp.permissionManager.removePlayer(event.getPlayer());
 		rscp.regionListProvider.removePlayer(event.getPlayer());
 	}
 }

src/main/java/ru/simsonic/rscPermissions/BukkitPluginMain.java

@@ -52,7 +52,8 @@ public final class BukkitPluginMain extends JavaPlugin
 	{
 		settings.readSettings();
 		// Register event's dispatcher
-		getServer().getPluginManager().registerEvents(maintenance, this);
+		maintenance.onEnable();
+		getServer().getPluginManager().registerEvents(bukkitListener, this);
 		regionUpdateObserver.registerListeners();
 		// WorldGuard, Residence and other possible region list providers
 		regionListProvider.integrate();