Don't fire block place event for non-replaceable blocks

src/main/java/com/moulberry/axiom/packet/impl/SetBlockPacketListener.java

@@ -137,23 +137,28 @@ public class SetBlockPacketListener implements PacketHandler {
             List<org.bukkit.block.BlockState> blockStates = new ArrayList<>();
             World world = player.serverLevel().getWorld();
             for (Map.Entry<BlockPos, BlockState> entry : blocks.entrySet()) {
+                BlockState existing = player.serverLevel().getBlockState(entry.getKey());
+                if (existing.canBeReplaced()) {
                     blockStates.add(new AxiomPlacingCraftBlockState(world, entry.getKey(), entry.getValue()));
                 }
+            }
 
-            Cancellable event = null;
+            if (!blockStates.isEmpty()) {
+                Cancellable event;
                 if (blockStates.size() > 1) {
                     event = CraftEventFactory.callBlockMultiPlaceEvent(player.serverLevel(),
                             player, hand, blockStates, blockHit.getBlockPos().getX(),
                             blockHit.getBlockPos().getY(), blockHit.getBlockPos().getZ());
-            } else if (blockStates.size() == 1) {
+                } else {
                     event = CraftEventFactory.callBlockPlaceEvent(player.serverLevel(),
                             player, hand, blockStates.get(0), blockHit.getBlockPos().getX(),
                             blockHit.getBlockPos().getY(), blockHit.getBlockPos().getZ());
                 }
-            if (event != null && event.isCancelled()) {
+                if (event.isCancelled()) {
                     return;
                 }
             }
+        }
 
         CraftWorld world = player.level().getWorld();