public class BaseDoc
        {
            public string User;
        }

        public class DocumentA: BaseDoc {}

        public class DocumentB: BaseDoc {}

        public class DocumentC: BaseDoc {}

        public class DocumentD: BaseDoc {}

        public class DocumentE: BaseDoc {}

        public class DocumentF: BaseDoc {}

        public class DocumentG: BaseDoc {}

        public class DocumentH: BaseDoc {}

        public class DocumentRepository<T> where T: BaseDoc
        {
            public List<T> documents;

            public DocumentRepository()
            {
                documents = new List<T>();
            }

            public IEnumerable<T> GetUserDocuments(string user)
            {
                return documents.Where(x => x.User == user);
            }
        }