Multi-Instance: Collection via process variable

[McMaster05]

Hi,
I am new to Camunda and trying to create a loop with a multi instance activity.
I want to pass the collection for the multiple runs as a variable from a user task before, but I can’t figure out the correct syntax to do so.
My attemps look like this:

Can anyone give me a hint on what I am doing wrong?

Thanks,
Manuel

[McMaster05]

I think I solved it:
For the expression now I set:

${S(mycollection).prop("list").elements()}

For the mycollection variable value I set

{"list": ["Hello", "World"]}