public HitsAggregationResult setSummaryClass(String summaryClass) {
        this.summaryClass = summaryClass;
        return this;
    }
Sets the summary class of hits to collect.

@param summaryClass the summary class to collect.
@return this, to allow chaining.
searchlib/src/main/java/com/yahoo/searchlib/aggregation/HitsAggregationResult.java