Can anyone help fix this old plugin? 

getting error:  "Error while compiling: HitInformer.cs(209,151): error CS0234: The type or namespace name `ObjectList' does not exist in the namespace `Facepunch'. Are you missing an assembly reference?"

// Reference: Newtonsoft.Json

using UnityEngine;
using Rust;
using System;
using System.Reflection;
using System.Collections;
using System.Collections.Generic;
using Oxide.Core;
using Oxide.Core.Plugins;
using Newtonsoft.Json;
using Newtonsoft.Json.Converters;

namespace Oxide.Plugins
{
	[Info("HitInformer", "Wolfs Darker", "1.0.0")]
	class HitInformer : RustPlugin
	{
		static String[] BODY_PARTS = { "SPINE", "LIP", "JAW", "NECK", "TAIL", "HIP", "FOOT", "PELVIS",
                                   "LEG", "HEAD", "ARM", "JOINT", "PENIS", "WING", "EYE",
                                   "EAR", "STOMACH", "MANE", "CLAVICLE", "FINGERS", "THIGH", "GROUP", "SHOULDER",
                                   "CALF", "TOE", "HAND", "KNEE", "FOREARM", "UPPERARM", "TONGUE", "SHIN", "ULNA", "ROOTBONE",
                                   "BROW" };

		static String[] BODY_NAMES = { "Spine", "Lips", "Jaw", "Neck",
                                  "Tail", "Hip", "Feet", "Pelvis", "Leg", "Head",
                                  "Arm", "Joint", "Penis", "Wing", "Eye", "Ear", "Stomach", "Mane", "Clavicle",
                                  "Fingers", "Thigh", "Group", "Shoulder", "Calf", "Toe",
                                  "Hand", "Knee", "Forearm", "Upperarm", "Tongue", "Shin",
                                  "Elbow", "Rootbone", "Brow" };

		static string ATTACK_GUI_DATA = @"[  
		                { 
							""name"": ""AttackHit"",
                            ""parent"": ""Overlay"",
                            ""components"":
                            [
                                {
                                     ""type"":""UnityEngine.UI.Image"",
                                     ""color"":""0.1 0.1 0.1 0.7"",
                                },
                                {
                                    ""type"":""RectTransform"",
                                    ""anchormin"": ""0.280 0.920"",
                                    ""anchormax"": ""0.720 0.990""
                                }
                            ]
                        },
						{
                            ""parent"": ""AttackHit"",
                            ""components"":
                            [
                                {
                                    ""type"":""UnityEngine.UI.Text"",
                                    ""text"":""{message}"",
                                    ""fontSize"":15,
                                    ""align"": ""MiddleCenter"",
                                },
                                {
                                    ""type"":""RectTransform"",
                                    ""anchormin"": ""0 0.350"",
                                    ""anchormax"": ""1 0.730""
                                }
                            ]
                        }
                    ]
                    ";

		static string TARGET_GUI_DATA = @"[  
		                { 
							""name"": ""TargetHit"",
                            ""parent"": ""Overlay"",
                            ""components"":
                            [
                                {
                                     ""type"":""UnityEngine.UI.Image"",
                                     ""color"":""0.1 0.1 0.1 0.7"",
                                },
                                {
                                    ""type"":""RectTransform"",
                                    ""anchormin"": ""0.280 0.840"",
                                    ""anchormax"": ""0.720 0.910""
                                }
                            ]
                        },
						{
                            ""parent"": ""TargetHit"",
                            ""components"":
                            [
                                {
                                    ""type"":""UnityEngine.UI.Text"",
                                    ""text"":""{message}"",
                                    ""fontSize"":15,
                                    ""align"": ""MiddleCenter"",
                                },
                                {
                                    ""type"":""RectTransform"",
                                    ""anchormin"": ""0 0.35"",
                                    ""anchormax"": ""1 0.73""
                                }
                            ]
                        }
                    ]
                    ";

		Configuration config = new Configuration();

		public class Configuration
		{
			public int message_delay;

			public List<String> players_list = new List<String>();
		}

		protected override void LoadDefaultConfig()
		{
			config.message_delay = 1;
			Config["configuration"] = config;
			SaveConfig();
		}

		void Loaded()
		{
			if(!permission.PermissionExists("hitinformer.use")) permission.RegisterPermission("hitinformer.use", this);
			Puts("HitInformer Loaded!");
		}

		[HookMethod("OnServerInitialized")]
		void OnServerInitialized()
		{
			try
			{
				if(!permission.PermissionExists("hitinformer.use")) permission.RegisterPermission("hitinformer.use", this);
				LoadConfig();
				config = JsonConvert.DeserializeObject<Configuration>(JsonConvert.SerializeObject(Config["configuration"]).ToString());
			}
			catch (Exception ex)
			{
				Puts("OnServerInitialized failed: " + ex.Message);
			}
		}

		void OnPlayerAttack(BasePlayer attacker, HitInfo hitInfo)
		{
			if (attacker == null || hitInfo == null || hitInfo.HitEntity == null || !(hitInfo.HitEntity is BasePlayer))
				return;
				//----------------------------> removed by isuelt    
				// if (!config.players_list.Contains(attacker.userID.ToString()))
				// return;

			String bone = StringPool.Get(hitInfo.HitBone).ToUpper();
			BasePlayer target = hitInfo.HitEntity as BasePlayer;
			if (target == null ) { return; }

			bone = bone.Replace("R_", "").Replace("L_", "");

			if (bone.Contains("SPINE"))
				bone = "SPINE";

			for (int i = 0; i < BODY_PARTS.Length; i++)
			{
				if (BODY_PARTS[i].Equals(bone))
				{
					bone = ", Body Part: " + BODY_NAMES[i];
					break;
				}
			}

			if (!bone.Contains("Body Part"))
			{
				bone = "";
			}

			sendGui(attacker, "You attacked <color=yellow>" + target.displayName + "</color>!(Distance: " + (int)attacker.Distance(target) + "m" + bone + ")", ATTACK_GUI_DATA);
			if (config.players_list.Contains(target.userID.ToString()))
				sendGui(target, "<color=yellow>" + attacker.displayName + "</color> attacked you!(Distance: " + (int)attacker.Distance(target) + "m)", TARGET_GUI_DATA);
			
			ConVar.Server.Log("oxide/logs/attack-log.txt", "|" + attacker.displayName +"|" + (int)attacker.Distance(target) +"m|"+ bone + "|" );
		}

		void sendGui(BasePlayer player, String message, String data)
		{
			// Changed by isuelt
			// CommunityEntity.ServerInstance.ClientRPCEx(new Network.SendInfo() { connection = player.net.connection }, null, "DestroyUI", data.Equals(TARGET_GUI_DATA) ? "TargetHit" : "AttackHit");

			CommunityEntity.ServerInstance.ClientRPCEx(new Network.SendInfo() { connection = player.net.connection }, null, "DestroyUI", new Facepunch.ObjectList(data.Equals(TARGET_GUI_DATA) ? "TargetHit" : "AttackHit", null, null, null, null));
			// Puts($"hitinformer AddGUI = " + data.Equals(TARGET_GUI_DATA) ? "TargetHit" : "AttackHit");
			// CommunityEntity.ServerInstance.ClientRPCEx(new Network.SendInfo() { connection = player.net.connection }, null, "AddUI", data.Replace("{message}", message));

			CommunityEntity.ServerInstance.ClientRPCEx(new Network.SendInfo() { connection = player.net.connection }, null, "AddUI", new Facepunch.ObjectList(data.Replace("{message}", message), null, null, null, null));
			// Puts($"hitinformer DestroyGUI = " + data.Replace("{message}", message));

			timer.Once(config.message_delay, () =>
										{
											// changed by isuelt
											// CommunityEntity.ServerInstance.ClientRPCEx(new Network.SendInfo() { connection = player.net.connection }, null, "DestroyUI", data.Equals(TARGET_GUI_DATA) ? "TargetHit" : "AttackHit");
											// Puts($"hitinformer delay ended - " + config.message_delay);
											CommunityEntity.ServerInstance.ClientRPCEx(new Network.SendInfo() { connection = player.net.connection }, null, "DestroyUI", new Facepunch.ObjectList(data.Equals(TARGET_GUI_DATA) ? "TargetHit" : "AttackHit", null, null, null, null));
											CommunityEntity.ServerInstance.ClientRPCEx(new Network.SendInfo() { connection = player.net.connection }, null, "DestroyUI", new Facepunch.ObjectList(data.Replace("{message}", message), null, null, null, null));
      				});
		}

		[ChatCommand("hitdelay")]
		void cmdHitDelay(BasePlayer player, string command, string[] args)
		{
			if (player.net.connection.authLevel < 2 && !permission.UserHasPermission(player.userID.ToString(), "hit_delay"))
			{
				SendReply(player, "You don't have access to this command.");
				return;
			}

			if (args.Length == 0)
			{
				SendReply(player, "Wrong command usage! Try again! (/hitdelay time (in seconds)");
				return;
			}

			try
			{
				config.message_delay = int.Parse(args[0]);
				Config["configuration"] = config;
				SaveConfig();
			}
			catch (Exception e)
			{
				SendReply(player, "Invalid time value! Try again! (/hitdelay time (in seconds)");
				Puts("Message delay error: " + e.Message);
			}
		}

		[ChatCommand("togglehit")]
		void cmdToggleHit(BasePlayer player, string command, string[] args)
		{
			if (player.net.connection.authLevel < 2 && !permission.UserHasPermission(player.userID.ToString(), "hitinformer.use"))
			{
				SendReply(player, "You don't have access to this command.");
				return;
			}

			if (config.players_list.Contains(player.userID.ToString()))
			{
				config.players_list.Remove(player.userID.ToString());
				SendReply(player, "Hit detector is Off!");
			}
			else
			{
				config.players_list.Add(player.userID.ToString());
				SendReply(player, "Hit detector is On!");
			}

			Config["configuration"] = config;
			SaveConfig();
		}
	}
}