@Override
    @SuppressWarnings("unchecked")
    public Q addJoinFlag(String flag, JoinFlag.Position position) {
        queryMixin.addJoinFlag(new JoinFlag(flag, position));
        return (Q) this;
    }
Add the given String literal as a join flag to the last added join

@param flag join flag
@param position position
@return the current object
querydsl-sql/src/main/java/com/querydsl/sql/ProjectableSQLQuery.java