Do both OpenStudio Zones and Spaces need to be Convex

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From the Energyplus input-output documentation, it is stated that zones should be convex for the solar radiation calculations to work correctly. But then this question mentions in its answer that the spaces need to be convex, but that one zone can include both spaces. Wouldn't this mean that the zone is non-convex? Or does the EPlus IO documentation refer to spaces not zones? Or is this just some OpenStudio terminology I am getting confused on?