Rebase #310 on Velocity 1.1.0

Totally untested, proceed with caution.

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/VelocityServerConnection.java

@@ -31,6 +31,7 @@ import java.nio.charset.StandardCharsets;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.UnaryOperator;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 public class VelocityServerConnection implements MinecraftConnectionAssociation, ServerConnection {

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -302,7 +302,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
       player.getConnection().delayedWrite(joinGame);
 
       destination.setActiveDimensionRegistry(joinGame.getDimensionRegistry()); // 1.16
-      player.getMinecraftConnection().delayedWrite(joinGame);
+      player.getConnection().delayedWrite(joinGame);
       // Required for Legacy Forge
       player.getPhase().onFirstJoin(player);
     } else {
@@ -317,18 +317,18 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
       // Most notably, by having the client accept the join game packet, we can work around the need
       // to perform entity ID rewrites, eliminating potential issues from rewriting packets and
       // improving compatibility with mods.
-      player.getMinecraftConnection().delayedWrite(joinGame);
+      player.getConnection().delayedWrite(joinGame);
       // Since 1.16 this dynamic changed:
       // We don't need to send two dimension swiches anymore!
       if (player.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_16) < 0) {
         int tempDim = joinGame.getDimension() == 0 ? -1 : 0;
-        player.getMinecraftConnection().delayedWrite(
+        player.getConnection().delayedWrite(
                 new Respawn(tempDim, joinGame.getPartialHashedSeed(), joinGame.getDifficulty(),
                         joinGame.getGamemode(), joinGame.getLevelType(),
                         false, joinGame.getDimensionInfo(), joinGame.getPreviousGamemode()));
       }
 
-      player.getMinecraftConnection().delayedWrite(
+      player.getConnection().delayedWrite(
           new Respawn(joinGame.getDimension(), joinGame.getPartialHashedSeed(),
               joinGame.getDifficulty(), joinGame.getGamemode(), joinGame.getLevelType(),
                   false, joinGame.getDimensionInfo(), joinGame.getPreviousGamemode()));

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

@@ -7,6 +7,7 @@ import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_13;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_14;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_15;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_16;
+import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_7_2;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_8;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9;
 import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9_4;