An unknown shrub in my garden

Dear Team of Experts: I have found a shrub growing in our garden which we didn’t plant – but because it didn’t look too unattractive, we have “allowed” it to stay up to now. We would like to re-plant it as part of a free-growing hedge bordering on our neighbour’s property. Unfortunately, we don’t know what this shrub is called, and therefore can’t research which conditions it requires and whether it is a good idea to keep it. For this reason, we have attached a photo. The stems are angular, which cannot unfortunately be seen on the photo. The shrub is now approx. 2 m high. We have always cut back the shrub at the sides, so that we cannot state its natural width. Maybe you can help us to provide this shrub with a name! The G. family from Dresden.