I have modified the 'Letter' activity to a custom activity. Need to populate custom attributes from activity screen to the opportunity screen when 'convert to opportunity' is selected.
My approach: Write a plug in that will execute when the opportunity is created. The plug in must loop through the activities in this opportunity that just got created. It has to check if the activity is of type 'letter' and populate the 'letter' attributes to the 'opportunity' attribute. I am stuck in this stage: how do I find the activity which exists in the opportunity's history using the plug in.