Edited Issue: Custom Xml and Json formatters : Overriding writetostreamasync taking CancellationToken do not get invoked [1415]

I am trying to customize the out of the box Xml and Json formatters by overriding WriteToStreamAsync methods taking in cancellation token.

_Issue_:
My overridden methods do not get called. This is because Xml and Json formatters themselves do not override the overloaded WriteToStreamAsync methods taking in cancellation token. This should also be a problem with ReadFromStreamAsync taking in cancellation token.

_Attached_ a katana repro.