How to serve an image with Scalatra - scalatra

Question

Is any version of Scalatra capable of serving images with the correct Content-Type header? I can't seem to suppress the automatic addition of charset.
Example of returning a File:
class MyServlet extends org.scalatra.ScalatraServlet {
get("/") {
contentType = "image/png"
new java.io.File("/tmp/test.png")
}
}
$ curl --head localhost:8080
HTTP/1.1 200 OK
Date: Thu, 01 Aug 2019 21:43:28 GMT
Content-Type: image/png;charset=utf-8
Transfer-Encoding: chunked
Server: Jetty(9.4.8.v20171121)
Example of returning an InputStream:
class MyServlet extends org.scalatra.ScalatraServlet {
get("/") {
contentType = "image/png"
new java.io.FileInputStream(new java.io.File("/tmp/test.png"))
}
}
$ curl --head localhost:8080
HTTP/1.1 200 OK
Date: Thu, 01 Aug 2019 21:49:52 GMT
Content-Type: image/png;charset=utf-8
Content-Length: 2881
Server: Jetty(9.4.8.v20171121)

Answer 1

One possible solution is setting ContentType and then writing binary directory to HttpServletResponse like this:
get("/image") {
contentType = "image/png"
val out = response.getOutputStream
// write binary to OutputStream here
...
// Prevent updating response headers in following processes
response.flushBuffer()
() // return Unit
}
By the way, I tried fixing this problem several years ago, but it has been reverted due to the backwards compatibility: https://github.com/scalatra/scalatra/pull/332