There are a few different cases where listings of memberships, groups, folders, etc. could make use of additional columns custom for each installation:

• membership attributes: notes, T&C agreement date; marker attributes
• group/folder attributes: provisioner metadata column in an app-aware way

Since it would be fully customizable, it doesn't need to be read-only; you could write a custom Java controller class, have a check button in the field that calls it to enable or disable marker attributes, or a notes link if there is a notes attribute for a membership.

If these were designed as jsp includes, that may be the easiest approach for allowing custom injections, without the high technical debt that would be the result of modifying the original jsp page. Proposed that there would need to be separate includes for the following:

• main section - set page scope variables
• list header
• list item rows