copying attachment from parent issue to subtask in transition

[Adrien kovanic]

hi, we are using JMWE  and creating a subtask in a transition from parent issue . works great. 

we are having an issue with adding attachments that have been uploaded through the transition screen

eg : we want to have the subtask created with the last attachment done via the transition screen 

we have been able to get something with : 

{{ issue.fields.attachment | last | field("self") }}

but it is not enough  (not working)

thanks a lot :)