The "Qsys System Design Components" section of the Quartus II handbook describes an Avalon-ST channel multiplexer core. The documentation states that a "value of 0 means that the optional channel signal is not used." When I set the "Channel Signal Width (bits)" field to 0 in Qsys, the wizard complains that channel isn't wide enough. What gives? How do I insert an Avalon-ST multiplexer that does not use the channel signal on the output?