RFR 8196298 Add null Reader and Writer

[Patrick Reinhart]

Hi Rémi,

I also found, that I missed the throw an ReadOnlyBufferException on a passed in read only CharBuffer.

> Am 01.02.2018 um 19:49 schrieb Remi Forax <forax at univ-mlv.fr>:
> 
> Hi Patrick,
> I believe read(CharBuffer), like read(char[], int, int), should test if there are remaining chars in the buffer.

Does it make sense to check for remaining chars in the buffer, wen the source is basically at the end of it’s data?

-Patrick