public static Expression<String> toLower(Expression<String> stringExpression) {
        if (stringExpression instanceof Constant) {
            Constant<String> constantExpression = (Constant<String>) stringExpression;
            return ConstantImpl.create(constantExpression.getConstant().toLowerCase());
        } else {
            return operation(String.class, Ops.LOWER, stringExpression);
        }
    }
Converts the given expression to lower(expression)

<p>Constants are lower()ed at creation time</p>

@param stringExpression the string to lower()
@return lower(stringExpression)
querydsl-core/src/main/java/com/querydsl/core/types/ExpressionUtils.java