Problem with PosePlugin

When people trying to use /lay in poseplugin it doesnt work and send this warns:
08.06 23:36:25 [Server] INFO Redvis_Sai issued server command: /lay
08.06 23:36:25 [Server] WARN java.lang.ClassNotFoundException: net.minecraft.server.v1_16_R3.PacketPlayOutBed
08.06 23:36:25 [Server] WARN at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:153)
08.06 23:36:25 [Server] WARN at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:114)
08.06 23:36:25 [Server] WARN at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
08.06 23:36:25 [Server] WARN at java.base/java.lang.Class.forName0(Native Method)
08.06 23:36:25 [Server] WARN at java.base/java.lang.Class.forName(Class.java:375)
08.06 23:36:25 [Server] WARN at net.apcat.simplesit.utils.Utils.getNMSClass(Utils.java:31)
08.06 23:36:25 [Server] WARN at net.apcat.simplesit.utils.NMS.(NMS.java:25)
08.06 23:36:25 [Server] WARN at net.apcat.simplesit.tasks.LayTask.(LayTask.java:49)
08.06 23:36:25 [Server] WARN at net.apcat.simplesit.SimpleSitPlayer.setLaying(SimpleSitPlayer.java:128)
08.06 23:36:25 [Server] WARN at net.apcat.simplesit.commands.LayCommand.onCommand(LayCommand.java:48)
08.06 23:36:25 [Server] WARN at org.bukkit.command.PluginCommand.execute(PluginCommand.java:45)
08.06 23:36:25 [Server] WARN at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:159)
08.06 23:36:25 [Server] WARN at org.bukkit.craftbukkit.v1_16_R3.CraftServer.dispatchCommand(CraftServer.java:827)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.PlayerConnection.handleCommand(PlayerConnection.java:2176)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.PlayerConnection.c(PlayerConnection.java:1991)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.PlayerConnection.a(PlayerConnection.java:1944)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.PacketPlayInChat.a(PacketPlayInChat.java:50)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.PacketPlayInChat.a(PacketPlayInChat.java:8)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.PlayerConnectionUtils.lambda$ensureMainThread$1(PlayerConnectionUtils.java:35)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.TickTask.run(SourceFile:18)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeTask(IAsyncTaskHandler.java:136)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeNext(IAsyncTaskHandler.java:109)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.MinecraftServer.bb(MinecraftServer.java:1265)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.MinecraftServer.executeNext(MinecraftServer.java:1258)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeAll(IAsyncTaskHandler.java:95)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.MinecraftServer.a(MinecraftServer.java:1394)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.MinecraftServer.w(MinecraftServer.java:1129)
08.06 23:36:25 [Server] WARN at net.minecraft.server.v1_16_R3.MinecraftServer.lambda$a$0(MinecraftServer.java:290)
08.06 23:36:25 [Server] WARN at java.base/java.lang.Thread.run(Thread.java:831)
08.06 23:36:25 [Server] ERROR null
08.06 23:36:25 [Server] INFO org.bukkit.command.CommandException: Unhandled exception executing command ‘lay’ in plugin SimpleSit v1.6.3
08.06 23:36:25 [Server] INFO at org.bukkit.command.PluginCommand.execute(PluginCommand.java:47) ~[patched_1.16.5.jar:git-Paper-722]
08.06 23:36:25 [Server] INFO at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:159) ~[patched_1.16.5.jar:git-Paper-722]
08.06 23:36:25 [Server] INFO at org.bukkit.craftbukkit.v1_16_R3.CraftServer.dispatchCommand(CraftServer.java:827) ~[patched_1.16.5.jar:git-Paper-722]
08.06 23:36:25 [Server] INFO at net.minecraft.server.v1_16_R3.PlayerConnection.handleCommand(PlayerConnection.java:2176) ~[patched_1.16.5.jar:git-Paper-722]
08.06 23:36:25 [Server] INFO at net.minecraft.server.v1_16_R3.PlayerConnection.c(PlayerConnection.java:1991) ~[patched_1.16.5.jar:git-Paper-722]
08.06 23:36:25 [Server] INFO at net.minecraft.server.v1_16_R3.PlayerConnection.a(PlayerConnection.java:1944) ~[patched_1.16.5.jar:git-Paper-722]
08.06 23:36:31 [Multicraft] Skipped 21 lines due to rate limit (40/s)