SPIGOT-7261: Add AsyncStructureSpawnEvent

By: Lauriichan <laura.endress@syntaxphoenix.com>

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

@@ -0,0 +1,95 @@
+package org.bukkit.event.world;
+
+import org.bukkit.World;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.HandlerList;
+import org.bukkit.generator.structure.Structure;
+import org.bukkit.util.BoundingBox;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Called when a {@link Structure} is naturally generated in the world.
+ */
+public class AsyncStructureSpawnEvent extends WorldEvent implements Cancellable {
+
+    private static final HandlerList handlers = new HandlerList();
+    private boolean cancelled = false;
+
+    private final Structure structure;
+    private final BoundingBox boundingBox;
+
+    private final int chunkX, chunkZ;
+
+    public AsyncStructureSpawnEvent(@NotNull World world, @NotNull Structure structure, @NotNull BoundingBox boundingBox, int chunkX, int chunkZ) {
+        super(world, true);
+        this.structure = structure;
+        this.boundingBox = boundingBox;
+        this.chunkX = chunkX;
+        this.chunkZ = chunkZ;
+    }
+
+    /**
+     * Get the structure reference that is generated.
+     *
+     * @return the structure
+     */
+    @NotNull
+    public Structure getStructure() {
+        return structure;
+    }
+
+    /**
+     * Get the bounding box of the structure.
+     *
+     * @return the bounding box
+     */
+    @NotNull
+    public BoundingBox getBoundingBox() {
+        return boundingBox;
+    }
+
+    /**
+     * Get the x coordinate of the origin chunk of the structure.
+     *
+     * <b>Note, it is not safe to attempt to retrieve or interact with this
+     * chunk. This event is informative only!</b>
+     *
+     * @return the chunk x coordinate
+     */
+    public int getChunkX() {
+        return chunkX;
+    }
+
+    /**
+     * Get the z coordinate of the origin chunk of the structure.
+     *
+     * <b>Note, it is not safe to attempt to retrieve or interact with this
+     * chunk. This event is informative only!</b>
+     *
+     * @return the chunk z coordinate
+     */
+    public int getChunkZ() {
+        return chunkZ;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return cancelled;
+    }
+
+    @Override
+    public void setCancelled(boolean cancel) {
+        cancelled = cancel;
+    }
+
+    @NotNull
+    @Override
+    public HandlerList getHandlers() {
+        return handlers;
+    }
+
+    @NotNull
+    public static HandlerList getHandlerList() {
+        return handlers;
+    }
+}