per specification, it has definition for $filter query parameter as: Include a subset of the members of a collection based on the expression
specified in the query parameters for this option - http://resourcecollection?$filter=SystemType eq 'Physical'
However, it seems to be make sense too when apply it to some of instance resource like: perform $select=Voltages&$filter=Voltages/Status/Health eq 'OK' on Chassis/Power resource to retrieve all healthy voltage sensors
May I have your opinion about this limitation? Thanks