PaperMC/paper-server/nms-patches/net/minecraft/world/level/block/BlockMonsterEggs.patch

--- a/net/minecraft/world/level/block/BlockMonsterEggs.java
+++ b/net/minecraft/world/level/block/BlockMonsterEggs.java
@@ -16,6 +16,8 @@
 import net.minecraft.world.level.block.state.IBlockData;
 import net.minecraft.world.level.block.state.properties.IBlockState;
 
+import org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason; // CraftBukkit
+
 public class BlockMonsterEggs extends Block {
 
     private final Block hostBlock;
@@ -42,7 +44,7 @@
 
         if (entitysilverfish != null) {
             entitysilverfish.moveTo((double) blockposition.getX() + 0.5D, (double) blockposition.getY(), (double) blockposition.getZ() + 0.5D, 0.0F, 0.0F);
-            worldserver.addFreshEntity(entitysilverfish);
+            worldserver.addFreshEntity(entitysilverfish, SpawnReason.SILVERFISH_BLOCK); // CraftBukkit - add SpawnReason
             entitysilverfish.spawnAnim();
         }