private void computeFillMarker() {
        if (isPresentationRequest(summaryRequestedInFill)) {
                fillMarkers.add(summaryRequestedInFill);
                if (askForFields != null) {
                    fillMarkers.add(syntheticName(askForFields));
                } else {
                    fillMarkers.add(summaryFromQuery);
                }
        } else if (askForFields != null) {
            fillMarkers.add(syntheticName(askForFields));
        } else {
            fillMarkers.add(summaryRequestedInFill);
            fillMarkers.add(askForSummary);
        }
    }
resolve summary class to use when none provided
container-search/src/main/java/com/yahoo/prelude/fastsearch/PartialSummaryHandler.java