An interface that can be implemented by any object that know how to turn itself into a ByteBuf.
All ByteBuf classes implement this interface, and return themselves.
Turn this object into a ByteBuf.
This does not increment the reference count of the ByteBuf instance.
The conversion or exposure of the ByteBuf must be idempotent, so that this method can be called
either once, or multiple times, without causing any change in program behaviour.