HttpResponseMessage を返すときの WebAPI Gzip 質問する

を返す WebAPI コントローラーがありHttpResponseMessage、gzip 圧縮を追加したいと考えています。これがサーバー コードです:

using System.Net.Http;
using System.Web.Http;
using System.Web;
using System.IO.Compression;

[Route("SomeRoute")]
public HttpResponseMessage Post([FromBody] string value)
{
    HttpContext context = HttpContext.Current;

    context.Response.Filter = new GZipStream(context.Response.Filter, CompressionMode.Compress);

    HttpContext.Current.Response.AppendHeader("Content-encoding", "gzip");
    HttpContext.Current.Response.Cache.VaryByHeaders["Accept-encoding"] = true;

    return new SomeClass().SomeRequest(value);
}

$.ajax({
    url: "/SomeRoute",
    type: "POST",
    cache: "false",
    data: SomeData,
    beforeSend: function (jqXHR) { jqXHR.setRequestHeader('Accept-Encoding', 'gzip'); },
    success: function(msg) { ... }

(failed)
net::ERR_CONTENT_DECODING_FAILED