I am developing a driver (In secure mode S2: 131) that needs multiChannelV4 and I have just noticed that the toString has not been implemented on version v4, with v3 the object gets printed correctly.
I have verified the issue with 2.2.3 and 2.2.4.139
I just noticed this today as well, could not figure out what I was doing wrong. Just wanted to update my driver from v3 to v4 but the command trace was coming out like you showed so I didn't know if it was going to work correctly.
Looks like this was fixed for 2.2.5 in some of the multichannel classes but not the v4 MultiChannelCmdEncap. Still getting this in my logs when trying to show the command instead of the actual command.