Concatenate values of checkboxes fields from Subtasks to parent using groovy script

[Maille Christine]

I have a CheckBoxes Custom Field available in Issue and associated SubTask.

When a Subtask in Done I would like to copy the values selected in the Subtask to the parent Issue.

If the Parent Issue has already some values set, I would like to have keep also the old values

Kind of "concatenation"

Do you have some sample of groovy scripts doing it.

Thank you in advance.

C.Maillé

[Maille Christine]

Dear all ,

I would like really some help on this topic.. 

Is somebody can give a solution

[Nic Brough _Adaptavist_]

How are you doing these check boxes?