Laurens-Packages/Packages/com.unity.shadergraph/Editor/Importers/ShaderSubGraphImporterEditor.cs

using UnityEditor;
#if UNITY_2020_2_OR_NEWER
using UnityEditor.AssetImporters;
#else
using UnityEditor.Experimental.AssetImporters;
#endif
using UnityEngine;
using Debug = System.Diagnostics.Debug;

namespace UnityEditor.ShaderGraph
{
    [CustomEditor(typeof(ShaderSubGraphImporter))]
    class ShaderSubGraphImporterEditor : ScriptedImporterEditor
    {
        public override bool showImportedObject => Unsupported.IsDeveloperMode();
        protected override bool needsApplyRevert => false;

        public override void OnInspectorGUI()
        {
            if (GUILayout.Button("Open Shader Editor"))
            {
                AssetImporter importer = target as AssetImporter;
                Debug.Assert(importer != null, "importer != null");
                ShaderGraphImporterEditor.ShowGraphEditWindow(importer.assetPath);
            }

            ApplyRevertGUI();
        }
    }
}