(bug) Errors in Unity 6000.2

[SubatomicPlanets]

Description

Unity 6000.2 updated the TreeView API and this package no longer works.
The HierarchyFolderIcon class is where the problems arise. Before the update this line worked properly:
prop_data = type_treeViewController.GetProperty("data", BindingAll);
But after the update this results in an Ambiguous match found error. This happens because Unity 6000.2 introduced a generic TreeViewItem type. I tried to get it working and managed in the end but it's not very nice:

I use this code to get prop_data instead so I get the generic type:

prop_data = type_treeViewController.GetProperties(BindingAll)
    .First(p => p.Name == "data" && p.PropertyType.IsGenericType);

Then I got rid of the meth_getRows and meth_isExpanded related code:

[System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE1006:Naming Styles", Justification = "Special naming scheme")]
private static MethodInfo meth_getRows;
[System.Diagnostics.CodeAnalysis.SuppressMessage("Style", "IDE1006:Naming Styles", Justification = "Special naming scheme")]
private static MethodInfo meth_isExpanded;

...

var type_iTreeViewDataSource = assembly.GetType("UnityEditor.IMGUI.Controls.ITreeViewDataSource");
meth_getRows = type_iTreeViewDataSource.GetMethod("GetRows");
meth_isExpanded = type_iTreeViewDataSource.GetMethod("IsExpanded", new Type[] { typeof(TreeViewItem) });

And then I get the methods in the RefreshFolderIcons function itself:

var rows = (IList<TreeViewItem<int>>)data.GetType().GetMethod("GetRows").Invoke(data, Array.Empty<object>());

...

bool isExpanded = (bool)data.GetType().GetMethods().First(p => p.Name == "IsExpanded").Invoke(data, new object[] { item.id });

It now uses the new generic API but it might be worse for performance since I get the methods every time RefreshFolderIcons is called. Ideally there would be a proper fix.

Great package by the way, thanks!

Environment

• Unity 6000.2.5
• Windows 10