public void CharsetTest()
{
ContentTypeBuilder b = new ContentTypeBuilder();
b.Set("text/html", "utf-8");
Assert.Equal("text/html; charset=utf-8", b.Build());
b.Set(MediaType.Application_json, Charset.Utf_8);
Assert.Equal("application/json; charset=utf-8", b.Build());
b.Reset();
Assert.Null(b.Build());
}