private void joinDocTypesFromUserQueryAndYql() {
        List<String> allSourceNames = new ArrayList<>(currentlyParsing.getSources().size() + yqlSources.size());
        if ( ! yqlSources.isEmpty()) {
            allSourceNames.addAll(currentlyParsing.getSources());
            allSourceNames.addAll(yqlSources);
        } else {
            // no sources == all sources in Vespa
        }
        indexFactsSession = indexFacts.newSession(allSourceNames, currentlyParsing.getRestrict());
        docTypes = new HashSet<>(indexFactsSession.documentTypes());
    }
The YQL query language.

This class <em>must</em> be kept in lockstep with {@link VespaSerializer}.
Adding anything here will usually require a corresponding addition in
VespaSerializer.

@author Steinar Knutsen
@author Stian Kristoffersen
@author Simon Thoresen Hult
container-search/src/main/java/com/yahoo/search/yql/YqlParser.java