public static void DispositionType_Roundtrip()
{
var cd = new ContentDisposition();
Assert.Equal("attachment", cd.DispositionType);
Assert.Empty(cd.Parameters);
cd.DispositionType = "hello";
Assert.Equal("hello", cd.DispositionType);
cd.DispositionType = "world";
Assert.Equal("world", cd.DispositionType);
Assert.Equal(0, cd.Parameters.Count);
}