What a partly failed DeleteMaterializationSet got through, attached to the error so a caller can
tell which materialized feature members are gone and which ones still need attention. The set
itself is left in place whenever any member failed, so a retry can still find the members.
What a partly failed DeleteMaterializationSet got through, attached to the error so a caller can tell which materialized feature members are gone and which ones still need attention. The set itself is left in place whenever any member failed, so a retry can still find the members.