Output of JSON containing backslashes leads to broken JSON

Reproduction steps:

• Create a page with the following content:

  {{velocity}}
  #if($request.outputSyntax == "plain")
    $response.setContentType('application/json')
  #end
  $jsontool.serialize("Something with \ backslash")
  {{/velocity}}
  

• Open the page in get mode with ?outputSyntax=plain

Expected result:

• You see "Something with \ backslash" in get mode and the obtained JSON is valid

Obtained result:

• Instead of the "\" you see a line return, and the JSON is marked as invalid because of it

Note: I tried using "\" and

\\ 

without any change on the resulted JSON validity.