RawFileBodyPart not found

Gatling (Open-Source)
1

Hi,
I’m using Gatling version 2.3.0. I want to upload a Json file but the method RawFileBodyPart could not be found

.exec(http("Import")
.post(requestSpecification + "/upload")
.headers(Common.headers_2)
.bodyPart(RawFileBodyPart("${File}").fileName("File").contentType("application/json").charset("charset=UTF-8")).asMultipartForm
.check(status.is(201)))


I also tried bodyPart.rawFileBodyPart, but it's still not found. Do you have any idea why I get this error ?

Thank You
2

I imported io.gatling.http:

import io.gatling.http._

When I trye to define: 
[...]
.bodyPart(io.gatling.http.HttpDsl.RawFileBodyPart("${File}")[...]

HttpDsl is not found in the io.gatling.http package. But when I open the io.gatling.http package, I see the class and the method I need.
Do you have any idea why ?