Add GolemConstructEvent

paper-api/src/main/java/io/papermc/paper/event/entity/GolemConstructEvent.java

@@ -0,0 +1,66 @@
+package io.papermc.paper.event.entity;
+
+import org.bukkit.block.Block;
+import org.bukkit.entity.Golem;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.HandlerList;
+import org.bukkit.event.entity.EntityEvent;
+import org.bukkit.event.entity.EntitySpawnEvent;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Unmodifiable;
+import org.jspecify.annotations.NullMarked;
+import java.util.List;
+
+/**
+ * Called just before a {@link Golem} spawns due to a pattern of blocks being constructed.
+ * <br>
+ * Note: This event is fired before {@link EntitySpawnEvent}, before the golem is added to the world,
+ * the success of this event does not guarantee the golem will actually spawn.
+ */
+@NullMarked
+public class GolemConstructEvent extends EntityEvent implements Cancellable {
+
+    private static final HandlerList HANDLER_LIST = new HandlerList();
+
+    private final List<Block> blocks;
+    private boolean cancelled;
+
+    @ApiStatus.Internal
+    public GolemConstructEvent(Golem golem, List<Block> blocks) {
+        super(golem);
+        this.blocks = List.copyOf(blocks);
+    }
+
+    @Override
+    public Golem getEntity() {
+        return (Golem) super.getEntity();
+    }
+
+    /**
+     * Get an immutable list of the blocks for this golem
+     *
+     * @return the golem blocks
+     */
+    public @Unmodifiable List<Block> getBlocks() {
+        return blocks;
+    }
+
+    @Override
+    public void setCancelled(final boolean cancel) {
+        this.cancelled = cancel;
+    }
+
+    @Override
+    public boolean isCancelled() {
+        return cancelled;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return HANDLER_LIST;
+    }
+
+    public static HandlerList getHandlerList() {
+        return HANDLER_LIST;
+    }
+}

paper-server/patches/sources/net/minecraft/world/level/block/CarvedPumpkinBlock.java.patch

@@ -8,7 +8,7 @@
                  this.replaceCopperBlockWithChest(level, copperGolemMatch);
                  copperGolem.spawn(this.getWeatherStateFromPattern(copperGolemMatch));
              }
-@@ -105,9 +_,22 @@
+@@ -105,9 +_,32 @@
      }
 
      private static void spawnGolemInWorld(final Level level, final BlockPattern.BlockPatternMatch match, final Entity golem, final BlockPos spawnPos) {
@@ -17,6 +17,16 @@
          golem.snapTo(spawnPos.getX() + 0.5, spawnPos.getY() + 0.05, spawnPos.getZ() + 0.5, 0.0F, 0.0F);
 -        level.addFreshEntity(golem);
 +        // Paper start
++        java.util.List<org.bukkit.block.Block> blocks = new java.util.ArrayList<>();
++        for (int x = 0; x < match.getWidth(); x++) {
++            for (int y = 0; y < match.getHeight(); y++) {
++                BlockInWorld block = match.getBlock(x, y, 0);
++                blocks.add(org.bukkit.craftbukkit.block.CraftBlock.at(level, block.getPos()));
++            }
++        }
++        if (!new io.papermc.paper.event.entity.GolemConstructEvent((org.bukkit.entity.Golem) golem.getBukkitEntity(), blocks).callEvent()) {
++            return;
++        }
 +        org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason spawnReason;
 +        if (golem.getType() == net.minecraft.world.entity.EntityType.SNOW_GOLEM) {
 +            spawnReason = org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason.BUILD_SNOWMAN;