PaperMC/nms-patches/BlockEnderPortal.patch

--- a/net/minecraft/server/BlockEnderPortal.java
+++ b/net/minecraft/server/BlockEnderPortal.java
@@ -1,5 +1,10 @@
 package net.minecraft.server;
 
+// CraftBukkit start
+import org.bukkit.event.entity.EntityPortalEnterEvent;
+import org.bukkit.event.player.PlayerTeleportEvent;
+// CraftBukkit end
+
 public class BlockEnderPortal extends BlockTileEntity {
 
     protected static final VoxelShape a = Block.a(0.0D, 0.0D, 0.0D, 16.0D, 12.0D, 16.0D);
@@ -28,6 +33,15 @@
                 return;
             }
 
+            // CraftBukkit start - Entity in portal
+            EntityPortalEnterEvent event = new EntityPortalEnterEvent(entity.getBukkitEntity(), new org.bukkit.Location(world.getWorld(), blockposition.getX(), blockposition.getY(), blockposition.getZ()));
+            world.getServer().getPluginManager().callEvent(event);
+
+            if (entity instanceof EntityPlayer) {
+                ((EntityPlayer) entity).a(worldserver, PlayerTeleportEvent.TeleportCause.END_PORTAL);
+                return;
+            }
+            // CraftBukkit end
             entity.a(worldserver);
         }