Paper/nms-patches/BlockConcretePowder.patch

--- a/net/minecraft/server/BlockConcretePowder.java
+++ b/net/minecraft/server/BlockConcretePowder.java
@@ -11,8 +11,8 @@
     }
 
     public void a(World world, BlockPosition blockposition, IBlockData iblockdata, IBlockData iblockdata1) {
-        if (iblockdata1.getMaterial().isLiquid()) {
-            world.setTypeAndData(blockposition, Blocks.dR.getBlockData().set(BlockCloth.COLOR, iblockdata.get(BlockConcretePowder.a)), 3);
+        if (iblockdata1.getMaterial().isLiquid() && world.getType(blockposition).getBlock() != Blocks.dR) { // CraftBukkit - don't double concrete
+            org.bukkit.craftbukkit.event.CraftEventFactory.handleBlockFormEvent(world, blockposition, Blocks.dR.getBlockData().set(BlockCloth.COLOR, iblockdata.get(BlockConcretePowder.a)), null); // CraftBukkit
         }
 
     }
@@ -36,7 +36,7 @@
         }
 
         if (flag) {
-            world.setTypeAndData(blockposition, Blocks.dR.getBlockData().set(BlockCloth.COLOR, iblockdata.get(BlockConcretePowder.a)), 3);
+            org.bukkit.craftbukkit.event.CraftEventFactory.handleBlockFormEvent(world, blockposition, Blocks.dR.getBlockData().set(BlockCloth.COLOR, iblockdata.get(BlockConcretePowder.a)), null); // CraftBukkit
         }
 
         return flag;