Don't attempt to load permissions data for login events cancelled at the lowest priority

Makes LuckPerms more compatible with "anti-bot" plugins.

bukkit/src/main/java/me/lucko/luckperms/bukkit/listeners/BukkitConnectionListener.java

@@ -81,7 +81,8 @@ public class BukkitConnectionListener extends AbstractConnectionListener impleme
     @EventHandler(priority = EventPriority.LOW)
     public void onPlayerPreLogin(AsyncPlayerPreLoginEvent e) {
         /* Called when the player first attempts a connection with the server.
-           Listening on LOW priority to allow plugins to modify username / UUID data here. (auth plugins) */
+           Listening on LOW priority to allow plugins to modify username / UUID data here. (auth plugins)
+           Also, give other plugins a chance to cancel the event. */
 
         /* wait for the plugin to enable. because these events are fired async, they can be called before
            the plugin has enabled.  */
@@ -95,6 +96,13 @@ public class BukkitConnectionListener extends AbstractConnectionListener impleme
             this.plugin.getLogger().info("Processing pre-login for " + e.getUniqueId() + " - " + e.getName());
         }
 
+        if (e.getLoginResult() != AsyncPlayerPreLoginEvent.Result.ALLOWED) {
+            // another plugin has disallowed the login.
+            this.plugin.getLogger().info("Another plugin has cancelled the connection for " + e.getUniqueId() + " - " + e.getName() + ". No permissions data will be loaded.");
+            this.deniedAsyncLogin.add(e.getUniqueId());
+            return;
+        }
+
         /* Actually process the login for the connection.
            We do this here to delay the login until the data is ready.
            If the login gets cancelled later on, then this will be cleaned up.

bungee/src/main/java/me/lucko/luckperms/bungee/listeners/BungeeConnectionListener.java

@@ -70,6 +70,12 @@ public class BungeeConnectionListener extends AbstractConnectionListener impleme
             this.plugin.getLogger().info("Processing pre-login for " + c.getUniqueId() + " - " + c.getName());
         }
 
+        if (e.isCancelled()) {
+            // another plugin has disallowed the login.
+            this.plugin.getLogger().info("Another plugin has cancelled the connection for " + c.getUniqueId() + " - " + c.getName() + ". No permissions data will be loaded.");
+            return;
+        }
+
         this.plugin.getBootstrap().getScheduler().executeAsync(() -> {
             /* Actually process the login for the connection.
                We do this here to delay the login until the data is ready.

nukkit/src/main/java/me/lucko/luckperms/nukkit/listeners/NukkitConnectionListener.java

@@ -60,12 +60,20 @@ public class NukkitConnectionListener extends AbstractConnectionListener impleme
     @EventHandler(priority = EventPriority.LOW)
     public void onPlayerPreLogin(PlayerAsyncPreLoginEvent e) {
         /* Called when the player first attempts a connection with the server.
-           Listening on LOW priority to allow plugins to modify username / UUID data here. (auth plugins) */
+           Listening on LOW priority to allow plugins to modify username / UUID data here. (auth plugins)
+           Also, give other plugins a chance to cancel the event. */
 
         if (this.plugin.getConfiguration().get(ConfigKeys.DEBUG_LOGINS)) {
             this.plugin.getLogger().info("Processing pre-login for " + e.getUuid() + " - " + e.getName());
         }
 
+        if (e.getLoginResult() != PlayerAsyncPreLoginEvent.LoginResult.SUCCESS) {
+            // another plugin has disallowed the login.
+            this.plugin.getLogger().info("Another plugin has cancelled the connection for " + e.getUuid() + " - " + e.getName() + ". No permissions data will be loaded.");
+            this.deniedAsyncLogin.add(e.getUuid());
+            return;
+        }
+
         /* Actually process the login for the connection.
            We do this here to delay the login until the data is ready.
            If the login gets cancelled later on, then this will be cleaned up.

sponge/src/main/java/me/lucko/luckperms/sponge/listeners/SpongeConnectionListener.java

@@ -59,7 +59,8 @@ public class SpongeConnectionListener extends AbstractConnectionListener {
     @IsCancelled(Tristate.UNDEFINED)
     public void onClientAuth(ClientConnectionEvent.Auth e) {
         /* Called when the player first attempts a connection with the server.
-           Listening on AFTER_PRE priority to allow plugins to modify username / UUID data here. (auth plugins) */
+           Listening on AFTER_PRE priority to allow plugins to modify username / UUID data here. (auth plugins)
+           Also, give other plugins a chance to cancel the event. */
 
         final GameProfile profile = e.getProfile();
         final String username = profile.getName().orElseThrow(() -> new RuntimeException("No username present for user " + profile.getUniqueId()));
@@ -68,6 +69,13 @@ public class SpongeConnectionListener extends AbstractConnectionListener {
             this.plugin.getLogger().info("Processing auth event for " + profile.getUniqueId() + " - " + profile.getName());
         }
 
+        if (e.isCancelled()) {
+            // another plugin has disallowed the login.
+            this.plugin.getLogger().info("Another plugin has cancelled the connection for " + profile.getUniqueId() + " - " + username + ". No permissions data will be loaded.");
+            this.deniedAsyncLogin.add(profile.getUniqueId());
+            return;
+        }
+
         /* Actually process the login for the connection.
            We do this here to delay the login until the data is ready.
            If the login gets cancelled later on, then this will be cleaned up.