NXmx: should NXdetector_channel in NXdetector be required?

[spc93]

This field probably doesn't make sense in many types of detector so would it be better to make it optional to avoid adding meaningless values or giving a validation error?

[phyy-nx]

Telco: this looks like a bug. Will check with dectris then add recommended=True.

[soph-dec]

Agreed, it makes no sense that this field is required, this is a bug. I think making it optional is enough though.