Send a dimension change upon join game packet now sent by bungeecord on 1.16

connector/src/main/java/org/geysermc/connector/network/translators/java/JavaJoinGameTranslator.java

@@ -52,6 +52,13 @@ public class JavaJoinGameTranslator extends PacketTranslator<ServerJoinGamePacke
     public void translate(ServerJoinGamePacket packet, GeyserSession session) {
         PlayerEntity entity = session.getPlayerEntity();
         entity.setEntityId(packet.getEntityId());
+        // If the player is already initialized and a join game packet is sent, they
+        // are swapping servers
+        if (session.isSpawned()) {
+            String fakeDim = entity.getDimension().equals(DimensionUtils.OVERWORLD) ? DimensionUtils.NETHER : DimensionUtils.OVERWORLD;
+            DimensionUtils.switchDimension(session, fakeDim);
+            DimensionUtils.switchDimension(session, packet.getDimension());
+        }
 
         AdventureSettingsPacket bedrockPacket = new AdventureSettingsPacket();
         bedrockPacket.setUniqueEntityId(session.getPlayerEntity().getGeyserId());