Add a CreateReason to PortalCreateEvent. Addresses BUKKIT-833

By: Sam Wilson <sam.wilson@gmail.com>

paper-api/src/main/java/org/bukkit/event/world/PortalCreateEvent.java

@@ -9,16 +9,19 @@ import java.util.ArrayList;
 import java.util.Collection;
 
 /**
- * Called when the world attempts to create a matching end to a portal
+ * Called when a portal is created
  */
 public class PortalCreateEvent extends WorldEvent implements Cancellable {
     private static final HandlerList handlers = new HandlerList();
     private boolean cancel = false;
     private final ArrayList<Block> blocks = new ArrayList<Block>();
+    private CreateReason reason = CreateReason.FIRE;
 
-    public PortalCreateEvent(final Collection<Block> blocks, final World world) {
+    public PortalCreateEvent(final Collection<Block> blocks, final World world, CreateReason reason) {
         super(world);
+
         this.blocks.addAll(blocks);
+        this.reason = reason;
     }
 
     /**
@@ -38,6 +41,15 @@ public class PortalCreateEvent extends WorldEvent implements Cancellable {
         this.cancel = cancel;
     }
 
+    /**
+     * Gets the reason for the portal's creation
+     *
+     * @return CreateReason for the portal's creation
+     */
+    public CreateReason getReason() {
+        return reason;
+    }
+
     @Override
     public HandlerList getHandlers() {
         return handlers;
@@ -46,4 +58,18 @@ public class PortalCreateEvent extends WorldEvent implements Cancellable {
     public static HandlerList getHandlerList() {
         return handlers;
     }
+
+    /**
+     * An enum to specify the various reasons for a portal's creation
+     */
+    public enum CreateReason {
+        /**
+         * When a portal is created 'traditionally' due to a portal frame being set on fire.
+         */
+        FIRE,
+        /**
+         * When a portal is created as a destination for an existing portal when using the custom PortalTravelAgent
+         */
+        OBC_DESTINATION
+    }
 }