fix crash

src/main/java/jp/stoic/minecraft/harvestgrasses/HarvestGrassesMod.java

@@ -1,22 +1,32 @@
 package jp.stoic.minecraft.harvestgrasses;
 
-import net.minecraft.init.Items;
+import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
+import net.minecraft.util.ResourceLocation;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.fml.common.Mod;
 import net.minecraftforge.fml.common.Mod.EventHandler;
 import net.minecraftforge.fml.common.event.FMLInitializationEvent;
 import net.minecraftforge.fml.common.event.FMLPreInitializationEvent;
-import net.minecraftforge.fml.common.registry.ForgeRegistries;
+import net.minecraftforge.fml.common.registry.GameRegistry;
+import net.minecraftforge.registries.IForgeRegistry;
 import org.apache.logging.log4j.Logger;
 
+import java.util.Arrays;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
 @Mod(modid = HarvestGrassesMod.MODID, name = HarvestGrassesMod.NAME, version = HarvestGrassesMod.VERSION)
 public class HarvestGrassesMod {
     static final String MODID = "harvestgrassesmod";
     static final String NAME = "Harvest Grasses Mod";
     static final String VERSION = "0.3";
 
     private static Logger logger;
+    private final static List<String> noDropItemNames = Arrays.asList(
+            "air", "barrier"
+    );
 
     @EventHandler
     public void preInit(FMLPreInitializationEvent event) {
@@ -25,9 +35,19 @@ public void preInit(FMLPreInitializationEvent event) {
 
     @EventHandler
     public void init(FMLInitializationEvent event) {
-        ForgeRegistries.ITEMS.getValuesCollection().stream()
-                .filter(item -> !Items.AIR.equals(item))
-                .forEach(item -> MinecraftForge.addGrassSeed(new ItemStack(item), 10));
+        IForgeRegistry<Item> itemRegistry = GameRegistry.findRegistry(Item.class);
+        Set<Item> noDropItems = noDropItemNames.stream()
+                .map(ResourceLocation::new)
+                .filter(itemRegistry::containsKey)
+                .map(itemRegistry::getValue)
+                .collect(Collectors.toSet());
+        itemRegistry.getValuesCollection().stream()
+                .filter(item -> !noDropItems.contains(item))
+                .forEach(this::addGrassSeed);
         logger.info("It's Harvest Time!");
     }
+
+    private void addGrassSeed(Item item) {
+        MinecraftForge.addGrassSeed(new ItemStack(item), 10);
+    }
 }