PaperMC/paper-server/nms-patches/net/minecraft/world/level/block/AzaleaBlock.patch

--- a/net/minecraft/world/level/block/AzaleaBlock.java
+++ b/net/minecraft/world/level/block/AzaleaBlock.java
@@ -12,6 +12,13 @@
 import net.minecraft.world.phys.shapes.VoxelShapeCollision;
 import net.minecraft.world.phys.shapes.VoxelShapes;
 
+// CraftBukkit start
+import org.bukkit.Location;
+import org.bukkit.TreeType;
+import org.bukkit.block.BlockState;
+import org.bukkit.event.world.StructureGrowEvent;
+// CraftBukkit end
+
 public class AzaleaBlock extends BlockPlant implements IBlockFragilePlantElement {
 
     private static final AzaleaTreeGrower TREE_GROWER = new AzaleaTreeGrower();
@@ -43,6 +50,29 @@
 
     @Override
     public void a(WorldServer worldserver, Random random, BlockPosition blockposition, IBlockData iblockdata) {
+        // CraftBukkit start
+        worldserver.captureTreeGeneration = true;
+        // CraftBukkit end
         AzaleaBlock.TREE_GROWER.a(worldserver, worldserver.getChunkProvider().getChunkGenerator(), blockposition, iblockdata, random);
+        // CraftBukkit start
+        worldserver.captureTreeGeneration = false;
+        if (worldserver.capturedBlockStates.size() > 0) {
+            TreeType treeType = BlockSapling.treeType;
+            BlockSapling.treeType = null;
+            Location location = new Location(worldserver.getWorld(), blockposition.getX(), blockposition.getY(), blockposition.getZ());
+            java.util.List<BlockState> blocks = new java.util.ArrayList<>(worldserver.capturedBlockStates.values());
+            worldserver.capturedBlockStates.clear();
+            StructureGrowEvent event = null;
+            if (treeType != null) {
+                event = new StructureGrowEvent(location, treeType, false, null, blocks);
+                org.bukkit.Bukkit.getPluginManager().callEvent(event);
+            }
+            if (event == null || !event.isCancelled()) {
+                for (BlockState blockstate : blocks) {
+                    blockstate.update(true);
+                }
+            }
+        }
+        // CraftBukkit end
     }
 }