How to add custom property in SlickGrid grouping?

Question

For my project I'm using draggable grouping. My requirement is that I should hide the column from the grid once it is grouped and add it back again to the grid once it is removed from the grouping. I'm doing this work inside onGroupChanged event callback for which I need some custom params, which gives me some information about the columns that are grouped which I will use as a param to the hide column method and some other validations. The onGroupChanged event args gives everything that is given inside the grouping object inside columndefinition. So if I can get a provision to set a custom param inside the grouping object in the columndefinition, I will use it for my operation. If there are any other way to achieve this kindly tell me. I am using the following interface

grouping.interface.ts