public void setReferable(boolean referable) {
        this.referable=referable;
        if (referable && getContextName()==null)
            setContextName("...");
        if (!referable && "...".equals(getContextName()))
            setContextName(null);
    }
Sets whether this ellipsis condition can be referred from a production or not
container-search/src/main/java/com/yahoo/prelude/semantics/rule/EllipsisCondition.java