JT-19611: Workflow collections clear the oldvalue on adding new values

1. create 2 issues
   
2. make the first one the parent of the second one# create 3 versions, e.g. '1', '2', '3'
   
3. set the parent 'Fix versions' to '1'

rule Add the new subtask 'Fix versions' to the parent 
 
when subtask of.isNotEmpty && Fix versions.added.isNotEmpty { 
  var parent = subtask of.first; 
  for each version in Fix versions.added { 
    message(version.name); 
    parent.Fix versions.add(version); 
  } 
}