This PR adds missing @Nullable annotations in ContentDisposition.Builder.

See 7f9349b7ae36af312c83ea1b9a9232e13490cfc3

Comment From: sdeleuze

Thanks, any reason with name(String name) does not get a @Nullable annotation in this PR?

Comment From: izeye

@sdeleuze Ah, it seems I just missed that. I added 8789f14 for it.

Comment From: sdeleuze

Merged, I added @Nullable on the Charset parameter as well.