Tabulator header filter list with optgroup

Using Tabulator 6.3 and header filters, did someone manage to build a list of grouped values ?I'm already feeding the values with a custom list built from an ajax call, but how to tell Tabulator to group these values ?

Here is my list

[{ value: "V1", group: "A group" },{ value: "V2", group: "A group" },{ value: "V3", group: "A group" },{ value: "V4", group: "A group" },{ value: "V12", machinelist: "Another group" },{ value: "V13", machinelist: "Another group" },{ value: "V14", machinelist: "Another group" },{ value: "V15", machinelist: "Another group" }]

I tried the groupBy option, no chance.

I get this with a standard array of values:

<select multiple><option value="V1">V1</option> <option value="V2">V2</option> <option value="V3">V3</option> <option value="V4">V4</option> <option value="V12">V12</option><option value="V13">V13</option><option value="V14">V14</option><option value="V15">V15</option></select>

What I getAnd would like to get something like this:

<select multiple><optgroup label="A group"><option value="V1">V1</option> <option value="V2">V2</option> <option value="V3">V3</option> <option value="V4">V4</option> </optgroup><optgroup label="Another group"><option value="V12">V12</option><option value="V13">V13</option><option value="V14">V14</option><option value="V15">V15</option></optgroup></select>

What I'd likeI feel I need to use the custom formatting option but do not see how for the header filter.Any idea ?

Edit, self answer: RTFM ! https://tabulator.info/docs/6.3/edit#editor-listI got there by looking at the source code for "listItemFormatter" that pointed me from this deprecated option to the editor.