PaperMC/nms-patches/BlockLever.patch

--- a/net/minecraft/server/BlockLever.java
+++ b/net/minecraft/server/BlockLever.java
@@ -3,6 +3,8 @@
 import java.util.Iterator;
 import javax.annotation.Nullable;
 
+import org.bukkit.event.block.BlockRedstoneEvent; // CraftBukkit
+
 public class BlockLever extends Block {
 
     public static final BlockStateEnum<BlockLever.EnumLeverPosition> FACING = BlockStateEnum.of("facing", BlockLever.EnumLeverPosition.class);
@@ -129,6 +131,20 @@
         if (world.isClientSide) {
             return true;
         } else {
+            // CraftBukkit start - Interact Lever
+            boolean powered = iblockdata.get(POWERED);
+            org.bukkit.block.Block block = world.getWorld().getBlockAt(blockposition.getX(), blockposition.getY(), blockposition.getZ());
+            int old = (powered) ? 15 : 0;
+            int current = (!powered) ? 15 : 0;
+
+            BlockRedstoneEvent eventRedstone = new BlockRedstoneEvent(block, old, current);
+            world.getServer().getPluginManager().callEvent(eventRedstone);
+
+            if ((eventRedstone.getNewCurrent() > 0) != (!powered)) {
+                return true;
+            }
+            // CraftBukkit end
+
             iblockdata = iblockdata.a((IBlockState) BlockLever.POWERED);
             world.setTypeAndData(blockposition, iblockdata, 3);
             float f3 = ((Boolean) iblockdata.get(BlockLever.POWERED)).booleanValue() ? 0.6F : 0.5F;