public void addSummaryClass(String name, Set<String> fields) {
        summaryClasses.put(name, fields);
    }
Adds a result which can be searched for and filled.
Summary fields starting by "a" are attributes, others are not.

@return true when replacing an existing &lt;query, result&gt; pair.
container-search/src/main/java/com/yahoo/search/searchchain/testutil/DocumentSourceSearcher.java