public OperationResult AcceptFriendRequest(long friendshipId)
{
var friendship = friendshipRepository.Get(friendshipId);
if (friendship == null)
{
return(OperationResult.Failed($"FriendRequest with ID = {friendshipId} does not exist"));
}
friendship.FriendshipStatus = FriendshipStatus.Accepted;
friendshipRepository.Save(friendship);
return(OperationResult.Success());
}