Resolve some warnings.

proxy/src/main/java/com/velocitypowered/proxy/protocol/ProtocolUtils.java

@@ -17,6 +17,11 @@ public enum ProtocolUtils {
   ;
   private static final int DEFAULT_MAX_STRING_SIZE = 65536; // 64KiB
 
+  /**
+   * Reads a Minecraft-style VarInt from the specified {@code buf}.
+   * @param buf the buffer to read from
+   * @return the decoded VarInt
+   */
   public static int readVarInt(ByteBuf buf) {
     int i = 0;
     int j = 0;
@@ -33,6 +38,11 @@ public enum ProtocolUtils {
     return i;
   }
 
+  /**
+   * Writes a Minecraft-style VarInt to the specified {@code buf}.
+   * @param buf the buffer to read from
+   * @param value the integer to write
+   */
   public static void writeVarInt(ByteBuf buf, int value) {
     while (true) {
       if ((value & 0xFFFFFF80) == 0) {
@@ -49,6 +59,13 @@ public enum ProtocolUtils {
     return readString(buf, DEFAULT_MAX_STRING_SIZE);
   }
 
+  /**
+   * Reads a VarInt length-prefixed string from the {@code buf}, making sure to not go over
+   * {@code cap} size.
+   * @param buf the buffer to read from
+   * @param cap the maximum size of the string, in UTF-8 character length
+   * @return the decoded string
+   */
   public static String readString(ByteBuf buf, int cap) {
     int length = readVarInt(buf);
     checkArgument(length >= 0, "Got a negative-length string (%s)", length);
@@ -140,7 +157,7 @@ public enum ProtocolUtils {
 
     public StateRegistry.PacketRegistry.ProtocolRegistry getProtocolRegistry(StateRegistry state,
                                                                     ProtocolVersion protocolVersion) {
-      return (this == SERVERBOUND ? state.SERVERBOUND : state.CLIENTBOUND)
+      return (this == SERVERBOUND ? state.serverbound : state.clientbound)
               .getProtocolRegistry(protocolVersion);
     }
   }

proxy/src/main/java/com/velocitypowered/proxy/protocol/StateRegistry.java

@@ -1,6 +1,5 @@
 package com.velocitypowered.proxy.protocol;
 
-import static com.velocitypowered.proxy.protocol.ProtocolUtils.Direction;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_10;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_11;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_11_1;
@@ -16,10 +15,9 @@ import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9_1;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9_2;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9_4;
 import static com.velocitypowered.api.network.ProtocolVersion.MINIMUM_VERSION;
+import static com.velocitypowered.proxy.protocol.ProtocolUtils.Direction;
 
-import com.google.common.collect.ImmutableBiMap;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableMap;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.packet.BossBar;
 import com.velocitypowered.proxy.protocol.packet.Chat;
@@ -59,111 +57,111 @@ public enum StateRegistry {
 
   HANDSHAKE {
     {
-      SERVERBOUND.register(Handshake.class, Handshake::new,
+      serverbound.register(Handshake.class, Handshake::new,
           genericMappings(0x00));
     }
   },
   STATUS {
     {
-      SERVERBOUND.register(StatusRequest.class, () -> StatusRequest.INSTANCE,
+      serverbound.register(StatusRequest.class, () -> StatusRequest.INSTANCE,
           genericMappings(0x00));
-      SERVERBOUND.register(StatusPing.class, StatusPing::new,
+      serverbound.register(StatusPing.class, StatusPing::new,
           genericMappings(0x01));
 
-      CLIENTBOUND.register(StatusResponse.class, StatusResponse::new,
+      clientbound.register(StatusResponse.class, StatusResponse::new,
           genericMappings(0x00));
-      CLIENTBOUND.register(StatusPing.class, StatusPing::new,
+      clientbound.register(StatusPing.class, StatusPing::new,
           genericMappings(0x01));
     }
   },
   PLAY {
     {
-      SERVERBOUND.fallback = false;
+      serverbound.fallback = false;
-      CLIENTBOUND.fallback = false;
+      clientbound.fallback = false;
 
-      SERVERBOUND.register(TabCompleteRequest.class, TabCompleteRequest::new,
+      serverbound.register(TabCompleteRequest.class, TabCompleteRequest::new,
           map(0x14, MINECRAFT_1_8, false),
           map(0x01, MINECRAFT_1_9, false),
           map(0x02, MINECRAFT_1_12, false),
           map(0x01, MINECRAFT_1_12_1, false));
-      SERVERBOUND.register(Chat.class, Chat::new,
+      serverbound.register(Chat.class, Chat::new,
           map(0x01, MINECRAFT_1_8, false),
           map(0x02, MINECRAFT_1_9, false),
           map(0x03, MINECRAFT_1_12, false),
           map(0x02, MINECRAFT_1_12_1, false),
           map(0x02, MINECRAFT_1_13, false));
-      SERVERBOUND.register(ClientSettings.class, ClientSettings::new,
+      serverbound.register(ClientSettings.class, ClientSettings::new,
           map(0x15, MINECRAFT_1_8, false),
           map(0x04, MINECRAFT_1_9, false),
           map(0x05, MINECRAFT_1_12, false),
           map(0x04, MINECRAFT_1_12_1, false),
           map(0x04, MINECRAFT_1_13, false));
-      SERVERBOUND.register(PluginMessage.class, PluginMessage::new,
+      serverbound.register(PluginMessage.class, PluginMessage::new,
           map(0x17, MINECRAFT_1_8, false),
           map(0x09, MINECRAFT_1_9, false),
           map(0x0A, MINECRAFT_1_12, false),
           map(0x09, MINECRAFT_1_12_1, false),
           map(0x0A, MINECRAFT_1_13, false));
-      SERVERBOUND.register(KeepAlive.class, KeepAlive::new,
+      serverbound.register(KeepAlive.class, KeepAlive::new,
           map(0x00, MINECRAFT_1_8, false),
           map(0x0B, MINECRAFT_1_9, false),
           map(0x0C, MINECRAFT_1_12, false),
           map(0x0B, MINECRAFT_1_12_1, false),
           map(0x0E, MINECRAFT_1_13, false));
 
-      CLIENTBOUND.register(BossBar.class, BossBar::new,
+      clientbound.register(BossBar.class, BossBar::new,
           map(0x0C, MINECRAFT_1_9, false),
           map(0x0C, MINECRAFT_1_12, false),
           map(0x0C, MINECRAFT_1_13, false));
-      CLIENTBOUND.register(Chat.class, Chat::new,
+      clientbound.register(Chat.class, Chat::new,
           map(0x02, MINECRAFT_1_8, true),
           map(0x0F, MINECRAFT_1_9, true),
           map(0x0F, MINECRAFT_1_12, true),
           map(0x0E, MINECRAFT_1_13, true));
-      CLIENTBOUND.register(TabCompleteResponse.class, TabCompleteResponse::new,
+      clientbound.register(TabCompleteResponse.class, TabCompleteResponse::new,
           map(0x3A, MINECRAFT_1_8, false),
           map(0x0E, MINECRAFT_1_9, false),
           map(0x0E, MINECRAFT_1_12, false));
-      CLIENTBOUND.register(PluginMessage.class, PluginMessage::new,
+      clientbound.register(PluginMessage.class, PluginMessage::new,
           map(0x3F, MINECRAFT_1_8, false),
           map(0x18, MINECRAFT_1_9, false),
           map(0x18, MINECRAFT_1_12, false),
           map(0x19, MINECRAFT_1_13, false));
-      CLIENTBOUND.register(Disconnect.class, Disconnect::new,
+      clientbound.register(Disconnect.class, Disconnect::new,
           map(0x40, MINECRAFT_1_8, false),
           map(0x1A, MINECRAFT_1_9, false),
           map(0x1A, MINECRAFT_1_12, false),
           map(0x1B, MINECRAFT_1_13, false));
-      CLIENTBOUND.register(KeepAlive.class, KeepAlive::new,
+      clientbound.register(KeepAlive.class, KeepAlive::new,
           map(0x00, MINECRAFT_1_8, false),
           map(0x1F, MINECRAFT_1_9, false),
           map(0x1F, MINECRAFT_1_12, false),
           map(0x21, MINECRAFT_1_13, false));
-      CLIENTBOUND.register(JoinGame.class, JoinGame::new,
+      clientbound.register(JoinGame.class, JoinGame::new,
           map(0x01, MINECRAFT_1_8, false),
           map(0x23, MINECRAFT_1_9, false),
           map(0x23, MINECRAFT_1_12, false),
           map(0x25, MINECRAFT_1_13, false));
-      CLIENTBOUND.register(Respawn.class, Respawn::new,
+      clientbound.register(Respawn.class, Respawn::new,
           map(0x07, MINECRAFT_1_8, true),
           map(0x33, MINECRAFT_1_9, true),
           map(0x34, MINECRAFT_1_12, true),
           map(0x35, MINECRAFT_1_12_2, true),
           map(0x38, MINECRAFT_1_13, true));
-      CLIENTBOUND.register(HeaderAndFooter.class, HeaderAndFooter::new,
+      clientbound.register(HeaderAndFooter.class, HeaderAndFooter::new,
           map(0x47, MINECRAFT_1_8, true),
           map(0x48, MINECRAFT_1_9, true),
           map(0x47, MINECRAFT_1_9_4, true),
           map(0x49, MINECRAFT_1_12, true),
           map(0x4A, MINECRAFT_1_12_1, true),
           map(0x4E, MINECRAFT_1_13, true));
-      CLIENTBOUND.register(TitlePacket.class, TitlePacket::new,
+      clientbound.register(TitlePacket.class, TitlePacket::new,
           map(0x45, MINECRAFT_1_8, true),
           map(0x45, MINECRAFT_1_9, true),
           map(0x47, MINECRAFT_1_12, true),
           map(0x48, MINECRAFT_1_12_1, true),
           map(0x4B, MINECRAFT_1_13, true));
-      CLIENTBOUND.register(PlayerListItem.class, PlayerListItem::new,
+      clientbound.register(PlayerListItem.class, PlayerListItem::new,
           map(0x38, MINECRAFT_1_8, false),
           map(0x2D, MINECRAFT_1_9, false),
           map(0x2D, MINECRAFT_1_12, false),
@@ -173,30 +171,30 @@ public enum StateRegistry {
   },
   LOGIN {
     {
-      SERVERBOUND.register(ServerLogin.class, ServerLogin::new,
+      serverbound.register(ServerLogin.class, ServerLogin::new,
           genericMappings(0x00));
-      SERVERBOUND.register(EncryptionResponse.class, EncryptionResponse::new,
+      serverbound.register(EncryptionResponse.class, EncryptionResponse::new,
           genericMappings(0x01));
-      SERVERBOUND.register(LoginPluginResponse.class, LoginPluginResponse::new,
+      serverbound.register(LoginPluginResponse.class, LoginPluginResponse::new,
           map(0x02, MINECRAFT_1_13, false));
 
-      CLIENTBOUND.register(Disconnect.class, Disconnect::new,
+      clientbound.register(Disconnect.class, Disconnect::new,
           genericMappings(0x00));
-      CLIENTBOUND.register(EncryptionRequest.class, EncryptionRequest::new,
+      clientbound.register(EncryptionRequest.class, EncryptionRequest::new,
           genericMappings(0x01));
-      CLIENTBOUND.register(ServerLoginSuccess.class, ServerLoginSuccess::new,
+      clientbound.register(ServerLoginSuccess.class, ServerLoginSuccess::new,
           genericMappings(0x02));
-      CLIENTBOUND.register(SetCompression.class, SetCompression::new,
+      clientbound.register(SetCompression.class, SetCompression::new,
           genericMappings(0x03));
-      CLIENTBOUND.register(LoginPluginMessage.class, LoginPluginMessage::new,
+      clientbound.register(LoginPluginMessage.class, LoginPluginMessage::new,
           map(0x04, MINECRAFT_1_13, false));
     }
   };
 
   public static final int STATUS_ID = 1;
   public static final int LOGIN_ID = 2;
-  public final PacketRegistry CLIENTBOUND = new PacketRegistry(Direction.CLIENTBOUND);
+  public final PacketRegistry clientbound = new PacketRegistry(Direction.CLIENTBOUND);
-  public final PacketRegistry SERVERBOUND = new PacketRegistry(Direction.SERVERBOUND);
+  public final PacketRegistry serverbound = new PacketRegistry(Direction.SERVERBOUND);
 
   public static class PacketRegistry {
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/netty/GS4QueryHandler.java

@@ -7,10 +7,10 @@ import com.google.common.cache.Cache;
 import com.google.common.cache.CacheBuilder;
 import com.google.common.collect.ImmutableSet;
 import com.velocitypowered.api.event.query.ProxyQueryEvent;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.plugin.PluginContainer;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.server.QueryResponse;
-import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.VelocityServer;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/LegacyDisconnect.java

@@ -12,7 +12,7 @@ public class LegacyDisconnect {
   }
 
   /**
-   * Converts a legacy response into a disconnect packet.
+   * Converts a legacy response into an legacy disconnect packet.
    * @param response the response to convert
    * @return the disconnect packet
    */
@@ -28,8 +28,16 @@ public class LegacyDisconnect {
     return new LegacyDisconnect(kickMessage);
   }
 
+  /**
+   * Converts a {@link TextComponent} into a legacy disconnect packet.
+   * @param component the component to convert
+   * @return the disconnect packet
+   */
   public static LegacyDisconnect from(TextComponent component) {
-    return new LegacyDisconnect(ComponentSerializers.LEGACY.serialize(component));
+    // We intentionally use the legacy serializers, because the old clients can't understand JSON.
+    @SuppressWarnings("deprecated")
+    String serialized = ComponentSerializers.LEGACY.serialize(component);
+    return new LegacyDisconnect(serialized);
   }
 
   public String getReason() {

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/LegacyHandshake.java

@@ -9,12 +9,12 @@ import io.netty.buffer.ByteBuf;
 public class LegacyHandshake implements MinecraftPacket {
 
   @Override
-  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
     throw new UnsupportedOperationException();
   }
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/LegacyPing.java

@@ -9,12 +9,12 @@ import io.netty.buffer.ByteBuf;
 public class LegacyPing implements MinecraftPacket {
 
   @Override
-  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+  public void decode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion protocolVersion) {
+  public void encode(ByteBuf buf, ProtocolUtils.Direction direction, ProtocolVersion version) {
     throw new UnsupportedOperationException();
   }
 

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/PlayerListItem.java

@@ -1,9 +1,9 @@
 package com.velocitypowered.proxy.protocol.packet;
 
 import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.player.TabListEntry;
 import com.velocitypowered.api.util.GameProfile;
-import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;

proxy/src/main/java/com/velocitypowered/proxy/protocol/util/PluginMessageUtil.java

@@ -5,8 +5,8 @@ import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
-import com.velocitypowered.api.util.ProxyVersion;
 import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.api.util.ProxyVersion;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.packet.PluginMessage;
 import io.netty.buffer.ByteBuf;

proxy/src/main/java/com/velocitypowered/proxy/tablist/VelocityTabList.java

@@ -4,7 +4,6 @@ import com.google.common.base.Preconditions;
 import com.velocitypowered.api.proxy.player.TabList;
 import com.velocitypowered.api.proxy.player.TabListEntry;
 import com.velocitypowered.api.util.GameProfile;
-import com.velocitypowered.api.util.UuidUtils;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.protocol.packet.HeaderAndFooter;
 import com.velocitypowered.proxy.protocol.packet.PlayerListItem;
@@ -136,6 +135,9 @@ public class VelocityTabList implements TabList {
           }
           break;
         }
+        default:
+          // Nothing we can do here
+          break;
       }
     }
   }

proxy/src/main/java/com/velocitypowered/proxy/util/VelocityChannelRegistrar.java

@@ -2,6 +2,7 @@ package com.velocitypowered.proxy.util;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.ChannelRegistrar;
 import com.velocitypowered.api.proxy.messages.LegacyChannelIdentifier;
@@ -12,7 +13,6 @@ import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
-import com.velocitypowered.api.network.ProtocolVersion;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class VelocityChannelRegistrar implements ChannelRegistrar {
@@ -72,6 +72,11 @@ public class VelocityChannelRegistrar implements ChannelRegistrar {
     return identifierMap.get(id);
   }
 
+  /**
+   * Returns all the channel names to register depending on the Minecraft protocol version.
+   * @param protocolVersion the protocol version in use
+   * @return the list of channels to register
+   */
   public Collection<String> getChannelsForProtocol(ProtocolVersion protocolVersion) {
     if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_13) >= 0) {
       return getModernChannelIds();