public Parsable setLanguage(Language language) {
        Objects.requireNonNull(language, "Language cannot be null");
        this.language = language;
        return this;
    }
Returns the language to use when parsing, with a text to use for detection if necessary.
if not decided by the item under parsing. This is never null or UNKNOWN
container-search/src/main/java/com/yahoo/search/query/parser/Parsable.java