When attempting to filter a list on optional fields, such as with 

/o2ims-infrastructureMonitoring/v1/alarmSubscriptions?filter=(eq,filter,'ACKNOWLEDGE')

, the API returns

{
  "detail": "failed to evaluate selector: failed to evaluate 'filter': map doesn't have a 'filter' key",
  "status": 400
}

. This seems to be a result of internal/search/path_evaluator.go:133, where the fact that the field does not get returned for some objects means that it fails the query on all objects.

Although this bug references AlarmSubscriptionInfo, it really applies to any object with filtering.

every o-cloud-manager release with filtering it seems

100%

    1. Perform API request as in the description where only some alarmSubscriptions have a filter specified
    2. Observe API result as in the description

400 Bad Request

As per v8 of the spec,

All attribute names that appear in the AlarmSubscriptionInfo and in data
types referenced from it shall be supported by the O-Cloud in the filter
expression.

I would expect a null/missing value to be incomparable and always not equal to other values, similar to how NaNs get handled. This means that querying (eq,'filter',ACKNOWLEDGE) would not include AlarmSubscriptionInfo without filter attributes but (neq,'filter',ACKNOWLEDGE) would include all matching AlarmSubscriptionInfo objects and every AlarmSubscriptionInfo without a filter attribute.