Merge pull request #96 from Mystalion/spawnegg-and-potions

support for rewriting SpawnEggs

pom.xml

@@ -1,14 +1,29 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>us.myles</groupId>
     <artifactId>ViaVersion</artifactId>
-    <version>1.0-SNAPSHOT</version>
+    <version>0.4.6</version>
     <build>
         <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-shade-plugin</artifactId>
+                <version>1.4</version>
+                <configuration>
+                    <createDependencyReducedPom>false</createDependencyReducedPom>
+                </configuration>
+                <executions>
+                    <execution>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>shade</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
@@ -18,8 +33,19 @@
                 </configuration>
             </plugin>
         </plugins>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
     </build>
     <dependencies>
+        <dependency>
+            <groupId>org.spacehq</groupId>
+            <artifactId>opennbt</artifactId>
+            <version>1.0</version>
+        </dependency>
         <dependency>
             <groupId>org.bukkit</groupId>
             <artifactId>bukkit</artifactId>
@@ -50,5 +76,9 @@
             <id>spigot-repo</id>
             <url>https://hub.spigotmc.org/nexus/content/repositories/snapshots/</url>
         </repository>
+        <repository>
+            <id>spacehq-repo</id>
+            <url>https://repo.spacehq.org/content/repositories/releases/</url>
+        </repository>
     </repositories>
 </project>

src/main/java/us/myles/ViaVersion/ViaVersionPlugin.java

@@ -14,6 +14,7 @@ import org.bukkit.inventory.ItemStack;
 import org.bukkit.plugin.java.JavaPlugin;
 import us.myles.ViaVersion.api.ViaVersion;
 import us.myles.ViaVersion.api.ViaVersionAPI;
+import us.myles.ViaVersion.commands.ViaVersionCommand;
 import us.myles.ViaVersion.handlers.ViaVersionInitializer;
 import us.myles.ViaVersion.util.ReflectionUtil;
 
@@ -38,7 +39,7 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI {
             return;
         }
 
-        getLogger().info("ViaVersion enabled, injecting. (Allows 1.8 to be accessed via 1.9)");
+        getLogger().info("ViaVersion " + getDescription().getVersion() + " is now enabled, injecting. (Allows 1.8 to be accessed via 1.9)");
         try {
             injectPacketHandler();
             System.setProperty("ViaVersion", getDescription().getVersion());
@@ -52,6 +53,7 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI {
                 setPorted(e.getPlayer().getUniqueId(), false);
             }
         }, this);
+        getCommand("viaversion").setExecutor(new ViaVersionCommand());
     }
 
     public void injectPacketHandler() throws Exception {
@@ -89,6 +91,11 @@ public class ViaVersionPlugin extends JavaPlugin implements ViaVersionAPI {
         return portedPlayers.contains(player.getUniqueId());
     }
 
+    @Override
+    public String getVersion() {
+        return getDescription().getVersion();
+    }
+
     public void setPorted(UUID id, boolean value) {
         if (value) {
             portedPlayers.add(id);

src/main/java/us/myles/ViaVersion/api/ViaVersionAPI.java

@@ -3,6 +3,11 @@ package us.myles.ViaVersion.api;
 import org.bukkit.entity.Player;
 
 public interface ViaVersionAPI {
-
+    /**
+     * Is player using 1.9?
+     * @param player
+     * @return
+     */
     boolean isPorted(Player player);
+    String getVersion();
 }

src/main/java/us/myles/ViaVersion/api/slot/ItemSlotRewriter.java

@@ -0,0 +1,191 @@
+package us.myles.ViaVersion.api.slot;
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.bukkit.Material;
+import org.spacehq.opennbt.tag.builtin.CompoundTag;
+import org.spacehq.opennbt.tag.builtin.StringTag;
+
+import io.netty.buffer.ByteBuf;
+
+import us.myles.ViaVersion.CancelException;
+import us.myles.ViaVersion.util.PacketUtil;
+
+public class ItemSlotRewriter {
+
+    public static void rewrite1_9To1_8(ByteBuf input, ByteBuf output) throws CancelException {
+        try {
+            ItemStack item = readItemStack(input);
+            fixIdsFrom1_9To1_8(item);
+            writeItemStack(item, output);
+        } catch (Exception e) {
+            System.out.println("Error while rewriting an item slot.");
+            e.printStackTrace();
+            throw new CancelException();
+        }
+    }
+
+    public static void rewrite1_8To1_9(ByteBuf input, ByteBuf output) throws CancelException {
+        try {
+            ItemStack item = readItemStack(input);
+            fixIdsFrom1_8To1_9(item);
+            writeItemStack(item, output);
+        } catch (Exception e) {
+            System.out.println("Error while rewriting an item slot.");
+            e.printStackTrace();
+            throw new CancelException();
+        }
+    }
+
+    public static void fixIdsFrom1_9To1_8(ItemStack item) {
+        if (item != null) {
+            if (item.id == Material.MONSTER_EGG.getId() && item.data == 0) {
+                CompoundTag tag = item.tag;
+                int data = 0;
+                if (tag != null && tag.get("EntityTag") instanceof CompoundTag) {
+                    CompoundTag entityTag = tag.get("EntityTag");
+                    if (entityTag.get("id") instanceof StringTag) {
+                        StringTag id = entityTag.get("id");
+                        data = ENTTIY_NAME_TO_ID.get(id.getValue());
+                    }
+                }
+                item.tag = null;
+                item.data = (short) data;
+            }
+        }
+    }
+
+    public static void fixIdsFrom1_8To1_9(ItemStack item) {
+        if (item != null) {
+            if (item.id == Material.MONSTER_EGG.getId() && item.data != 0) {
+                CompoundTag tag = item.tag;
+                if (tag == null) {
+                    tag = new CompoundTag("tag");
+                }
+                CompoundTag entityTag = new CompoundTag("EntityTag");
+                StringTag id = new StringTag("id", ENTTIY_ID_TO_NAME.get(Integer.valueOf(item.data)));
+                entityTag.put(id);
+                tag.put(entityTag);
+                item.tag = tag;
+                item.data = 0;
+            }
+        }
+    }
+
+    public static ItemStack readItemStack(ByteBuf input) throws IOException {
+        short id = input.readShort();
+        if (id < 0) {
+            return null;
+        } else {
+            ItemStack item = new ItemStack();
+            item.id = id;
+            item.amount = input.readByte();
+            item.data = input.readShort();
+            item.tag = PacketUtil.readNBT(input);
+            return item;
+        }
+    }
+
+    public static void writeItemStack(ItemStack item, ByteBuf output) throws IOException {
+        if (item == null) {
+            output.writeShort(-1);
+        } else {
+            output.writeShort(item.id);
+            output.writeByte(item.amount);
+            output.writeShort(item.data);
+            PacketUtil.writeNBT(output, item.tag);
+        }
+    }
+
+    public static class ItemStack {
+
+        private short id;
+        private byte amount;
+        private short data;
+        private CompoundTag tag;
+
+        public static ItemStack fromBukkit(org.bukkit.inventory.ItemStack stack) {
+            ItemStack item = new ItemStack();
+            item.id = (short) stack.getTypeId();
+            item.amount = (byte) stack.getAmount();
+            item.data = stack.getData().getData();
+            // TODO: nbt
+            return item;
+        }
+    }
+
+    private static Map<String, Integer> ENTTIY_NAME_TO_ID = new HashMap<>();
+    private static Map<Integer, String> ENTTIY_ID_TO_NAME = new HashMap<>();
+
+    static {
+        register(1, "Item");
+        register(2, "XPOrb");
+        register(7, "ThrownEgg");
+        register(8, "LeashKnot");
+        register(9, "Painting");
+        register(10, "Arrow");
+        register(11, "Snowball");
+        register(12, "Fireball");
+        register(13, "SmallFireball");
+        register(14, "ThrownEnderpearl");
+        register(15, "EyeOfEnderSignal");
+        register(16, "ThrownPotion");
+        register(17, "ThrownExpBottle");
+        register(18, "ItemFrame");
+        register(19, "WitherSkull");
+        register(20, "PrimedTnt");
+        register(21, "FallingSand");
+        register(22, "FireworksRocketEntity");
+        register(30, "ArmorStand");
+        register(40, "MinecartCommandBlock");
+        register(41, "Boat");
+        register(42, "MinecartRideable");
+        register(43, "MinecartChest");
+        register(44, "MinecartFurnace");
+        register(45, "MinecartTNT");
+        register(46, "MinecartHopper");
+        register(47, "MinecartSpawner");
+        register(48, "Mob");
+        register(49, "Monster");
+        register(50, "Creeper");
+        register(51, "Skeleton");
+        register(52, "Spider");
+        register(53, "Giant");
+        register(54, "Zombie");
+        register(55, "Slime");
+        register(56, "Ghast");
+        register(57, "PigZombie");
+        register(58, "Enderman");
+        register(59, "CaveSpider");
+        register(60, "Silverfish");
+        register(61, "Blaze");
+        register(62, "LavaSlime");
+        register(63, "EnderDragon");
+        register(64, "WitherBoss");
+        register(65, "Bat");
+        register(66, "Witch");
+        register(67, "Endermite");
+        register(68, "Guardian");
+        register(90, "Pig");
+        register(91, "Sheep");
+        register(92, "Cow");
+        register(93, "Chicken");
+        register(94, "Squid");
+        register(95, "Wolf");
+        register(96, "MushroomCow");
+        register(97, "SnowMan");
+        register(98, "Ozelot");
+        register(99, "VillagerGolem");
+        register(100, "EntityHorse");
+        register(101, "Rabbit");
+        register(120, "Villager");
+        register(200, "EnderCrystal");
+    }
+
+    private static void register(Integer id, String name) {
+        ENTTIY_ID_TO_NAME.put(id, name);
+        ENTTIY_NAME_TO_ID.put(name, id);
+    }
+}

src/main/java/us/myles/ViaVersion/commands/ViaVersionCommand.java

@@ -0,0 +1,48 @@
+package us.myles.ViaVersion.commands;
+
+import org.bukkit.Bukkit;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandExecutor;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+import us.myles.ViaVersion.api.ViaVersion;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Created by fillefilip8 on 2016-03-03.
+ */
+public class ViaVersionCommand implements CommandExecutor {
+
+    @Override
+    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
+        if (sender.hasPermission("viaversion.admin")) {
+            if (args.length == 0) {
+                sender.sendMessage(color("&aViaVersion &c" + ViaVersion.getInstance().getVersion()));
+                sender.sendMessage(color("&6Commands:"));
+                sender.sendMessage(color("&2/viaversion list &7- &6Shows lists of all 1.9 clients and 1.8 clients."));
+            } else if (args.length == 1) {
+                if (args[0].equalsIgnoreCase("list")) {
+                    List<String> portedPlayers = new ArrayList<String>();
+                    List<String> normalPlayers = new ArrayList<String>();
+                    for (Player p : Bukkit.getOnlinePlayers()) {
+                        if (ViaVersion.getInstance().isPorted(p)) {
+                            portedPlayers.add(p.getName());
+                        } else {
+                            normalPlayers.add(p.getName());
+                        }
+                    }
+
+                    sender.sendMessage(color("&8[&61.9&8]: &b" + portedPlayers.toString()));
+                    sender.sendMessage(color("&8[&61.8&8]: &b" + normalPlayers.toString()));
+                }
+            }
+
+        }
+        return false;
+    }
+    public String color(String string){
+        return string.replace("&", "§");
+    }
+}

src/main/java/us/myles/ViaVersion/metadata/MetadataRewriter.java

@@ -11,6 +11,8 @@ import org.bukkit.util.Vector;
 
 import io.netty.buffer.ByteBuf;
 
+import us.myles.ViaVersion.api.slot.ItemSlotRewriter;
+import us.myles.ViaVersion.api.slot.ItemSlotRewriter.ItemStack;
 import us.myles.ViaVersion.util.PacketUtil;
 
 public class MetadataRewriter {
@@ -92,7 +94,9 @@ public class MetadataRewriter {
                                 output.writeBoolean(((Byte) value).byteValue() != 0);
                             break;
                         case Slot:
-                            PacketUtil.writeItem(value, output);
+                            ItemStack item = (ItemStack) value;
+                            ItemSlotRewriter.fixIdsFrom1_8To1_9(item);
+                            ItemSlotRewriter.writeItemStack(item, output);
                             break;
                         case Position:
                             Vector vector = (Vector) value;
@@ -148,8 +152,13 @@ public class MetadataRewriter {
                 case String:
                     entries.add(new Entry(index, PacketUtil.readString(buf)));
                     break;
-                case Slot:
+                case Slot: {
-                    entries.add(new Entry(index, PacketUtil.readItem(buf)));
+                    try {
+                        entries.add(new Entry(index, ItemSlotRewriter.readItemStack(buf)));
+                    } catch (Exception e) {
+                        e.printStackTrace();
+                    }
+                }
                     break;
                 case Position: {
                     int x = buf.readInt();

src/main/java/us/myles/ViaVersion/transformers/IncomingTransformer.java

@@ -5,6 +5,7 @@ import org.bukkit.inventory.ItemStack;
 import us.myles.ViaVersion.CancelException;
 import us.myles.ViaVersion.ConnectionInfo;
 import us.myles.ViaVersion.ViaVersionPlugin;
+import us.myles.ViaVersion.api.slot.ItemSlotRewriter;
 import us.myles.ViaVersion.packets.PacketType;
 import us.myles.ViaVersion.packets.State;
 import us.myles.ViaVersion.util.PacketUtil;
@@ -126,7 +127,7 @@ public class IncomingTransformer {
             output.writeByte(button);
             output.writeShort(action);
             output.writeByte(mode);
-            output.writeBytes(input);
+            ItemSlotRewriter.rewrite1_9To1_8(input, output);
             return;
         }
         if (packet == PacketType.PLAY_CLIENT_SETTINGS) {
@@ -179,22 +180,14 @@ public class IncomingTransformer {
             int hand = PacketUtil.readVarInt(input);
 
             ItemStack inHand = ViaVersionPlugin.getHandItem(info);
-            Object item = null;
             try {
-                Method m = ReflectionUtil.obc("inventory.CraftItemStack").getDeclaredMethod("asNMSCopy", ItemStack.class);
+                us.myles.ViaVersion.api.slot.ItemSlotRewriter.ItemStack item = us.myles.ViaVersion.api.slot.ItemSlotRewriter.ItemStack.fromBukkit(inHand);
-                item = m.invoke(null, inHand);
+                ItemSlotRewriter.fixIdsFrom1_9To1_8(item);
-            } catch (NoSuchMethodException e) {
+                ItemSlotRewriter.writeItemStack(item, output);
-                e.printStackTrace();
+            } catch (Exception e) {
-            } catch (ClassNotFoundException e) {
-                e.printStackTrace();
-            } catch (InvocationTargetException e) {
-                e.printStackTrace();
-            } catch (IllegalAccessException e) {
                 e.printStackTrace();
             }
 
-            PacketUtil.writeItem(item, output);
-
             short curX = input.readUnsignedByte();
             output.writeByte(curX);
             short curY = input.readUnsignedByte();
@@ -211,26 +204,25 @@ public class IncomingTransformer {
             output.writeByte(255);
             // write item in hand
             ItemStack inHand = ViaVersionPlugin.getHandItem(info);
-            Object item = null;
             try {
-                Method m = ReflectionUtil.obc("inventory.CraftItemStack").getDeclaredMethod("asNMSCopy", ItemStack.class);
+                us.myles.ViaVersion.api.slot.ItemSlotRewriter.ItemStack item = us.myles.ViaVersion.api.slot.ItemSlotRewriter.ItemStack.fromBukkit(inHand);
-                item = m.invoke(null, inHand);
+                ItemSlotRewriter.fixIdsFrom1_9To1_8(item);
-            } catch (NoSuchMethodException e) {
+                ItemSlotRewriter.writeItemStack(item, output);
-                e.printStackTrace();
+            } catch (Exception e) {
-            } catch (ClassNotFoundException e) {
-                e.printStackTrace();
-            } catch (InvocationTargetException e) {
-                e.printStackTrace();
-            } catch (IllegalAccessException e) {
                 e.printStackTrace();
             }
-            PacketUtil.writeItem(item, output);
 
             output.writeByte(-1);
             output.writeByte(-1);
             output.writeByte(-1);
             return;
         }
+        if (packet == PacketType.PLAY_CREATIVE_INVENTORY_ACTION) {
+            short slot = input.readShort();
+            output.writeShort(slot);
+
+            ItemSlotRewriter.rewrite1_9To1_8(input, output);
+        }
         output.writeBytes(input);
     }
 }

src/main/java/us/myles/ViaVersion/transformers/OutgoingTransformer.java

@@ -11,6 +11,7 @@ import us.myles.ViaVersion.CancelException;
 import us.myles.ViaVersion.ConnectionInfo;
 import us.myles.ViaVersion.ViaVersionPlugin;
 import us.myles.ViaVersion.api.ViaVersion;
+import us.myles.ViaVersion.api.slot.ItemSlotRewriter;
 import us.myles.ViaVersion.metadata.MetadataRewriter;
 import us.myles.ViaVersion.packets.PacketType;
 import us.myles.ViaVersion.packets.State;
@@ -225,7 +226,9 @@ public class OutgoingTransformer {
                 slot += 1; // add 1 so it's now 2-5
             }
             PacketUtil.writeVarInt(slot, output);
-            output.writeBytes(input);
+            
+            ItemSlotRewriter.rewrite1_8To1_9(input, output);
+            return;
         }
         if (packet == PacketType.PLAY_ENTITY_METADATA) {
             int id = PacketUtil.readVarInt(input);
@@ -342,6 +345,28 @@ public class OutgoingTransformer {
             output.writeBytes(input);
             return;
         }
+        if (packet == PacketType.PLAY_SET_SLOT) {
+            int windowId = input.readUnsignedByte();
+            output.writeByte(windowId);
+
+            short slot = input.readShort();
+            output.writeShort(slot);
+
+            ItemSlotRewriter.rewrite1_8To1_9(input, output);
+            return;
+        }
+        if (packet == PacketType.PLAY_WINDOW_ITEMS) {
+            int windowId = input.readUnsignedByte();
+            output.writeByte(windowId);
+
+            short count = input.readShort();
+            output.writeShort(count);
+
+            for (int i = 0; i < count; i++) {
+                ItemSlotRewriter.rewrite1_8To1_9(input, output);
+            }
+            return;
+        }
         if (packet == PacketType.PLAY_SPAWN_MOB) {
             int id = PacketUtil.readVarInt(input);
             PacketUtil.writeVarInt(id, output);

src/main/java/us/myles/ViaVersion/util/PacketUtil.java

@@ -3,6 +3,8 @@ package us.myles.ViaVersion.util;
 import com.google.common.base.Charsets;
 import com.google.common.base.Preconditions;
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufInputStream;
+import io.netty.buffer.ByteBufOutputStream;
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.ByteToMessageDecoder;
 import io.netty.handler.codec.MessageToByteEncoder;
@@ -11,6 +13,9 @@ import us.myles.ViaVersion.chunks.PacketChunk;
 import us.myles.ViaVersion.chunks.PacketChunkData;
 
 import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.DataOutputStream;
+import java.io.IOException;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.nio.ByteBuffer;
@@ -21,6 +26,9 @@ import java.util.BitSet;
 import java.util.List;
 import java.util.UUID;
 
+import org.spacehq.opennbt.NBTIO;
+import org.spacehq.opennbt.tag.builtin.CompoundTag;
+
 public class PacketUtil {
     private static Method DECODE_METHOD;
     private static Method ENCODE_METHOD;
@@ -42,6 +50,25 @@ public class PacketUtil {
         }
     }
 
+    public static CompoundTag readNBT(ByteBuf input) throws IOException {
+        int readerIndex = input.readerIndex();
+        byte b = input.readByte();
+        if (b == 0) {
+            return null;
+        } else {
+            input.readerIndex(readerIndex);
+            return (CompoundTag) NBTIO.readTag(new DataInputStream(new ByteBufInputStream(input)));
+        }
+    }
+
+    public static void writeNBT(ByteBuf output, CompoundTag tag) throws IOException {
+        if (tag == null) {
+            output.writeByte(0);
+        } else {
+            NBTIO.writeTag(new DataOutputStream(new ByteBufOutputStream(output)), tag);
+        }
+    }
+
     public static List<Object> callDecode(ByteToMessageDecoder decoder, ChannelHandlerContext ctx, Object input) {
         List<Object> output = new ArrayList<Object>();
         try {
@@ -354,45 +381,6 @@ public class PacketUtil {
         return output;
     }
 
-    public static void writeItem(Object value, ByteBuf output) {
-        try {
-            Class<?> serializer = ReflectionUtil.nms("PacketDataSerializer");
-            Object init = serializer.getDeclaredConstructor(ByteBuf.class).newInstance(output);
-            Method toCall = init.getClass().getDeclaredMethod("a", ReflectionUtil.nms("ItemStack"));
-            toCall.invoke(init, value);
-        } catch (ClassNotFoundException e) {
-            e.printStackTrace();
-        } catch (NoSuchMethodException e) {
-            e.printStackTrace();
-        } catch (InstantiationException e) {
-            e.printStackTrace();
-        } catch (IllegalAccessException e) {
-            e.printStackTrace();
-        } catch (InvocationTargetException e) {
-            e.printStackTrace();
-        }
-    }
-
-    public static Object readItem(ByteBuf output) {
-        try {
-            Class<?> serializer = ReflectionUtil.nms("PacketDataSerializer");
-            Object init = serializer.getDeclaredConstructor(ByteBuf.class).newInstance(output);
-            Method toCall = init.getClass().getDeclaredMethod("i");
-            return toCall.invoke(init);
-        } catch (ClassNotFoundException e) {
-            e.printStackTrace();
-        } catch (NoSuchMethodException e) {
-            e.printStackTrace();
-        } catch (InstantiationException e) {
-            e.printStackTrace();
-        } catch (IllegalAccessException e) {
-            e.printStackTrace();
-        } catch (InvocationTargetException e) {
-            e.printStackTrace();
-        }
-        return null;
-    }
-
     public static long[] readBlockPosition(ByteBuf buf) {
         long val = buf.readLong();
         long x = (val >> 38); // signed

src/main/java/us/myles/ViaVersion/util/ReflectionUtil.java

@@ -27,6 +27,18 @@ public class ReflectionUtil {
         return m.invoke(o);
     }
 
+    public static <T> T getStatic(Class<?> clazz, String f, Class<T> t) throws NoSuchFieldException, IllegalAccessException {
+        Field field = clazz.getDeclaredField(f);
+        field.setAccessible(true);
+        return (T) field.get(null);
+    }
+
+    public static <T> T get(Object instance, Class<?> clazz, String f, Class<T> t) throws NoSuchFieldException, IllegalAccessException {
+        Field field = clazz.getDeclaredField(f);
+        field.setAccessible(true);
+        return (T) field.get(instance);
+    }
+
     public static <T> T get(Object o, String f, Class<T> t) throws NoSuchFieldException, IllegalAccessException {
         Field field = o.getClass().getDeclaredField(f);
         field.setAccessible(true);

src/main/resources/plugin.yml

@@ -1,6 +1,11 @@
 name: ViaVersion
 main: us.myles.ViaVersion.ViaVersionPlugin
 author: _MylesC
-version: 0.4.6
+version: ${version}
 load: startup
 loadbefore: [ProtocolLib, ProxyPipe]
+commands:
+  viaversion:
+    description: Shows ViaVersion Version and more.
+    permission: viaversion.admin
+    aliases: [viaver]