PaperMC/nms-patches/ItemWaterLily.patch

--- a/net/minecraft/server/ItemWaterLily.java
+++ b/net/minecraft/server/ItemWaterLily.java
@@ -24,7 +24,15 @@
                 IBlockData iblockdata = world.getType(blockposition);
 
                 if (iblockdata.getMaterial() == Material.WATER && ((Integer) iblockdata.get(BlockFluids.LEVEL)).intValue() == 0 && world.isEmpty(blockposition1)) {
+                    // CraftBukkit start - special case for handling block placement with water lilies
+                    org.bukkit.block.BlockState blockstate = org.bukkit.craftbukkit.block.CraftBlockState.getBlockState(world, blockposition1.getX(), blockposition1.getY(), blockposition1.getZ());
                     world.setTypeAndData(blockposition1, Blocks.WATERLILY.getBlockData(), 11);
+                    org.bukkit.event.block.BlockPlaceEvent placeEvent = org.bukkit.craftbukkit.event.CraftEventFactory.callBlockPlaceEvent(world, entityhuman, enumhand, blockstate, blockposition.getX(), blockposition.getY(), blockposition.getZ());
+                    if (placeEvent != null && (placeEvent.isCancelled() || !placeEvent.canBuild())) {
+                        blockstate.update(true, false);
+                        return new InteractionResultWrapper(EnumInteractionResult.PASS, itemstack);
+                    }
+                    // CraftBukkit end
                     if (entityhuman instanceof EntityPlayer) {
                         CriterionTriggers.x.a((EntityPlayer) entityhuman, blockposition1, itemstack);
                     }