A ChunkedConversionSink is used to transmit data more efficiently between two converters during chunked conversions.
The basic ChunkedConversionSink is just a Sink, and converters should
work with a plain Sink, but may work more efficiently with certain
specialized types of ChunkedConversionSink.
It is recommended that implementations of ChunkedConversionSink extend
this class, to inherit any further methods that may be added to the class.