@Override
    public String toString() {
        return "field '" + name + "' type " + type.stringValue() + "" +
                (mandatory?" (mandatory)":"") + (!overridable?" (not overridable)":"");
    }
Returns a copy of this with the type set to the argument type
container-search/src/main/java/com/yahoo/search/query/profile/types/FieldDescription.java