Re: RFR [10]: 8185362: Replace use of AtomicReferenceFieldUpdater from BufferedInputStream with Unsafe

[Martin Buchholz]

This comment still seems applicable.  Can we move it into the docstring for
buf?

We use nullness
-     * of buf[] as primary indicator that this stream is closed. (The
-     * "in" field is also nulled out on close.)