Fix cancel checking causing errors

java/patchbukkit/src/main/java/org/patchbukkit/events/PatchBukkitEventFactory.java

@@ -2,6 +2,7 @@ package org.patchbukkit.events;
 
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
+import org.bukkit.event.Event;
 import org.bukkit.event.player.PlayerJoinEvent;
 import org.bukkit.event.player.PlayerQuitEvent;
 import net.kyori.adventure.text.Component;
@@ -37,6 +38,13 @@ public class PatchBukkitEventFactory {
         return new PlayerQuitEvent(player, quitMessage, PlayerQuitEvent.QuitReason.DISCONNECTED);
     }
 
+    /**
+     * Check if an event implements Cancellable.
+     */
+    public static boolean isCancellable(@NotNull Event event) {
+        return event instanceof org.bukkit.event.Cancellable;
+    }
+
     /**
      * Look up a player by UUID string. Returns null with a warning if not found.
      */

rust/src/java/plugin/event_manager.rs

@@ -51,13 +51,22 @@ impl EventManager {
             ],
         )?;
 
-        let cancelled = match jvm.invoke(
+        let is_cancellable: bool = jvm.to_rust(jvm.invoke_static(
+            "org.patchbukkit.events.PatchBukkitEventFactory",
+            "isCancellable",
+            &[InvocationArg::from(jvm.clone_instance(&j_event)?)],
+        )?)?;
+
+        let cancelled = match is_cancellable {
+            true => match jvm.invoke(
                 &jvm.clone_instance(&j_event)?,
                 "isCancelled",
                 InvocationArg::empty(),
             ) {
                 Ok(instance) => jvm.to_rust::<bool>(instance).unwrap_or(false),
                 Err(_) => false,
+            },
+            false => false,
         };
 
         Ok(cancelled)