add shelf inventory type

Author: Lulu13022002

paper-api/src/main/java/org/bukkit/event/inventory/InventoryType.java

@@ -143,6 +143,10 @@ public enum InventoryType {
      * Pseudo chiseled bookshelf inventory, with 6 slots of undefined type.
      */
     CHISELED_BOOKSHELF(6, "Chiseled Bookshelf", null, false),
+    /**
+     * Pseudo shelf inventory, with 3 slots of undefined type.
+     */
+    SHELF(3, "Shelf", null, false),
     /**
      * Pseudo jukebox inventory with 1 slot of undefined type.
      */

paper-server/src/main/java/org/bukkit/craftbukkit/inventory/CraftInventory.java

@@ -20,6 +20,7 @@
 import net.minecraft.world.level.block.entity.Hopper;
 import net.minecraft.world.level.block.entity.JukeboxBlockEntity;
 import net.minecraft.world.level.block.entity.LecternBlockEntity;
+import net.minecraft.world.level.block.entity.ShelfBlockEntity;
 import net.minecraft.world.level.block.entity.ShulkerBoxBlockEntity;
 import net.minecraft.world.level.block.entity.SmokerBlockEntity;
 import org.bukkit.Location;
@@ -517,6 +518,8 @@ public InventoryType getType() {
             return InventoryType.LECTERN;
         } else if (this.inventory instanceof ChiseledBookShelfBlockEntity) {
             return InventoryType.CHISELED_BOOKSHELF;
+        } else if (this.inventory instanceof ShelfBlockEntity) {
+            return InventoryType.SHELF;
         } else if (this instanceof CraftInventoryLoom) {
             return InventoryType.LOOM;
         } else if (this instanceof CraftInventoryCartography) {