UnityEditor.AssetPreview.GetMiniTypeThumbnailFromClassID C# (CSharp) Method

        internal static extern Texture2D GetMiniTypeThumbnailFromClassID(int classID);
        internal static bool HasAnyNewPreviewTexturesAvailable()

 public ComponentElement(int level, string name, string menuPath, string commandString)
 {
     this.level    = level;
     this.typeName = name.Replace(" ", string.Empty);
     this.menuPath = menuPath;
     if (commandString.StartsWith("SCRIPT"))
     {
         Texture miniThumbnail = (Texture)AssetPreview.GetMiniThumbnail(EditorUtility.InstanceIDToObject(int.Parse(commandString.Substring(6))));
         this.content = new GUIContent(name, miniThumbnail);
     }
     else
     {
         int classID = int.Parse(commandString);
         this.content = new GUIContent(name, (Texture)AssetPreview.GetMiniTypeThumbnailFromClassID(classID));
     }
 }