private static Expression<?> unwrap(Expression<?> expr) {
        expr = ExpressionUtils.extract(expr);
        if (expr instanceof Operation && ((Operation<?>) expr).getOperator() == Ops.ALIAS) {
            return ((Operation<?>) expr).getArg(0);
        }
        return expr;
    }
{@code ConstantHidingExpression} removes constants from the argument list and injects them back into the result chain
@param <T>
querydsl-core/src/main/java/com/querydsl/core/support/ConstantHidingExpression.java