private Item collapsePhrase(PhraseItem root) {
        if (root.getItemCount() == 1)
            return root.getItem(0);
        else
            return root;
    }
Make single item phrases in query into single word items.

@author Steinar Knutsen
container-search/src/main/java/com/yahoo/prelude/querytransform/CollapsePhraseSearcher.java