%dw 2.0
output multipart/form-data boundary="---------------------------9051914041544843365972754266"
---
{
parts : {
    partOne : {
        headers : {
            "Content-Type": "text/plain"
            },
        content : "content 1"
        },
    partTwo : {
        headers : {
            "Content-Disposition" : {
                "name": "partTwo",
                "filename": "a.html"
                },
            "Content-Type" : "text/html"
         },
        content : "<html><body><h1>Titel</h1></body></html>"
        }
    }
}