ошибка при создании мода на Unity

Assets/Editor/ContentTool.cs(44,4): error CS0103: The name `EditorAssetBundleHelper' does not exist in the current context ошибка в 44 строке, я не совсем опытный, по этому не могу решить проблему вот полный код

using UnityEditor;
using UnityEngine;
using System.IO;
namespace SDG.Unturned.Tools
{
    /// <summary>
    /// Simple tool to export all new assetbundles. 
    /// </summary>
    public class ContentTool : EditorWindow 
    {
        [MenuItem("Window/Unturned/Content Tool")]
        public static void ShowWindow() 
        {
            GetWindow(typeof(ContentTool));
        }
        protected Vector2 ScrollPosition;
        protected virtual bool IsContentBundle(string AssetBundleName)
        {
            return AssetBundleName.EndsWith(".content");
        }
        protected virtual string GetContentBundleExportPath(string AssetBundleName)
        {
            return EditorPrefs.GetString(AssetBundleName + "_ExportPath");
        }
        protected virtual void SetContentBundleExportPath(string AssetBundleName, string Path)
        {
            EditorPrefs.SetString(AssetBundleName + "_ExportPath", Path);
        }
        protected virtual void BuildContentBundle(string AssetBundleName)
        {
            string OutputPath = GetContentBundleExportPath(AssetBundleName);
            if(string.IsNullOrEmpty(OutputPath))
            {
                Debug.LogWarning("Output path unset for: " + AssetBundleName);
                return;
            }
            EditorAssetBundleHelper.Build(AssetBundleName, OutputPath, false);
        }
        protected virtual void OnGUI_ContentBundles()
        {
            string[] AssetBundles = AssetDatabase.GetAllAssetBundleNames();
            foreach(string AssetBundleName in AssetBundles)
            {
                if(!IsContentBundle(AssetBundleName))
                    continue;
                GUILayout.BeginHorizontal();
                GUILayout.Label(AssetBundleName);
                string CurrentPath = GetContentBundleExportPath(AssetBundleName);
                bool HasPath = !string.IsNullOrEmpty(CurrentPath);
                if(GUILayout.Button(new GUIContent("...", CurrentPath)))
                {
                    string NewPath = EditorUtility.OpenFolderPanel("Content Bundle", CurrentPath, "");
                    SetContentBundleExportPath(AssetBundleName, NewPath);
                }
                bool WasEnabled = GUI.enabled;
                GUI.enabled = HasPath && WasEnabled;
                if(GUILayout.Button("Export"))
                {
                    BuildContentBundle(AssetBundleName);
                }
                GUI.enabled = WasEnabled;
                GUILayout.EndHorizontal();
            }
        }
        protected virtual void OnGUI()
        {
            ScrollPosition = GUILayout.BeginScrollView(ScrollPosition);
            OnGUI_ContentBundles();
            GUILayout.EndScrollView();
        }
        private void OnEnable()
        {
            titleContent = new GUIContent("Content Tool");
        }
    }
}