Groovy DataGridBuilder varying columns

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Hi,

I got stuck on a groovy rule to build a DataGridBuilder with varying columns and don't know how to achive that. Here is my case.

Dimension period = operation.application.getDimension("Period",cube)
def rolling_periods = period.getEvaluatedMembers('&RollingMths',cube)

So, &RollingMths is a sub var, e.g. Apr:Dec

And I can get rolling_periods as [Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec] with no issue.

However, I need to build a DataGridBuilder as below

……………..

DataGridBuilder gridbuilder = cube.dataGridBuilder("MM/DD/YYYY",SYSTEM_USER)
gridbuilder.addPov(****)
gridbuilder.addColumn(rolling_periods.toString())