Accessing line_item properties in handlebars

I am trying to map the properties (an array of objects) from our shopify line_items to the Items : Descriptions in NetSuite.

Following the pattern I see for mapping line_item values that comes out of the box with the order flows, I cam up with this:

{{jsonSerialize line_items.[*].properties}}

The result of this is mapping the entirety of the first line_item into the description, which overflows the 4000 character limit.

I am assuming line_items.[*] doesn't work the same way inside the handlebars.

How can I access that value?

Thanks