public static WindowOver<Double> regrR2(Expression<? extends Number> arg1, Expression<? extends Number> arg2) {
        return new WindowOver<Double>(Double.class, SQLOps.REGR_R2, arg1, arg2);
    }
REGR_R2 returns the coefficient of determination (also called R-squared or goodness of fit) for the regression.

@param arg1 first arg
@param arg2 second arg
@return regr_r2(arg1, arg2)
querydsl-sql/src/main/java/com/querydsl/sql/SQLExpressions.java