How to update datagridcomboboxColumn itemsource?

Question

I have implemented a datagrid with some datagrid columns.

One of these columns are a DatagridComboboxColumn. That has itemsource binding to an ObservableCollection list from my Viewmodel.

How do i update the itemsource, so i can see the new list on the UI? The list is changing from the getter, that means I can't use OnPropertyChange. Is there any way around updating the UI From ViewModel or what should be the way to go here?

ViewModel property:

    private ObservableCollection<string> usedHMDGroups = new ObservableCollection<string>();
    private ObservableCollection<string> startHMDGroups = new ObservableCollection<string>{
                "136b6405",
                "136b6406",
                "136b6407",
                "136b6408",
                "136b6409",
                "136b6410",
                "None"
    };
    public ObservableCollection<string> HMDGroups
    {
        get
        {
            ObservableCollection<string> HMDGroupList = new ObservableCollection<string>(startHMDGroups.Except(usedHMDGroups));
            return HMDGroupList;

        }
        set 
        {
            OnPropertyChange("HMDGroups");
            
        }
    }

DatagridComboBoxColumn from datagrid:

                <DataGridComboBoxColumn x:Name="hmdComboCol" Header="HMD Group" 
                                    SelectedValueBinding="{Binding HMDGroup, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" 
                                    ItemsSource="{Binding Path=HMDGroups, Mode=TwoWay, Source={StaticResource ComboItems}}"/>

Answer 1

I found out, that i could just set the itemsource of the column again to the same list. This will use the getter again.

hmdComboCol.ItemsSource = vhitems.HMDGroups;