public static <A extends Comparable<? super A>> ComparableExpression<A> avg(CollectionExpression<?,A> col) {
        return Expressions.comparableOperation((Class) col.getParameter(0), Ops.QuantOps.AVG_IN_COL, (Expression<?>) col);
    }
Create a avg(col) expression

@param col collection
@return avg(col)
querydsl-jpa/src/main/java/com/querydsl/jpa/JPAExpressions.java