Upload multiple items in one shipment with csv/xlsx upload

Hi, easyship developers. In easyship doc, it is explained that we can specify the items of a shipment as an array, like this:

    "items": [
      {
        "description": "Silk dress",
        "sku": "test",
        "actual_weight": 1.2,
        "height": 10,
        "width": 15,
        "length": 20,
        "category": "fashion",
        "declared_currency": "SGD",
        "declared_customs_value": 100
      }
    ]

However, if I would like to create a shipment by uploading csv/xlsx, there is only one column of "Item Length (cm)", "Item Height (cm)", etc. How can I specify multiple items in one shipment (in one package)?

Thank you.