private String getIndex(String field) {
        Preconditions.checkArgument(indexFactsSession.isIndex(field), "Field '%s' does not exist.", field);
        //return indexFactsSession.getCanonicName(field);
        return field;
    }
Translates a list of grouping requests on JSON form to a list in the grouping language form
container-search/src/main/java/com/yahoo/search/query/SelectParser.java