public static String quotedSummaryClassName(String summaryClass, Set<String> summaryFields) {
        if (isDefaultRequest(summaryClass) && ! summaryFields.isEmpty()) {
            return syntheticName(summaryFields);
        } else if (summaryClass == null) {
            return "[null]";
        } else {
            return "'" + summaryClass + "'";
        }
    }
resolve summary class to use when none provided
container-search/src/main/java/com/yahoo/prelude/fastsearch/PartialSummaryHandler.java