private String getSpaceSeparated(List<String> terms) {
        StringBuilder builder = new StringBuilder();
        for (Iterator<String> i = terms.iterator(); i.hasNext(); ) {
            builder.append(i.next());
            if (i.hasNext())
                builder.append(" ");
        }
        return builder.toString();
    }
Returns a read only view of the terms produced by this, never null
container-search/src/main/java/com/yahoo/prelude/semantics/rule/LiteralPhraseProduction.java