I currently have a Automation set up to create a new work item in JPD when a user submits a service desk ticket. I am looking to copy over 2 multi select fields, but I either run into an issue of it not copying over or I get the error below:

The Json snippet I am using to make this copy is below. Let me know if you can help:
{
"fields": {
"customfield_17735.asJsonStringArray": "triggerIssue.customfield_18495.asJsonStringArray",
"customfield_17587.asJsonStringArray": "triggerIssue.customfield_18496.asJsonStringArray"
}
}