@SuppressWarnings("unchecked")
    public <RT> Q union(Path<?> alias, SubQueryExpression<RT>... sq) {
        return from((Expression) UnionUtils.union(Arrays.asList(sq), (Path) alias, false));
    }
Creates an union expression for the given subqueries

@param <RT>
@param alias alias for union
@param sq subqueries
@return the current object
querydsl-sql/src/main/java/com/querydsl/sql/ProjectableSQLQuery.java