`len(m.attached)` was used without locking.
Also, use gofumpt to make whitespace usage more consistent.
Change-Id: Ifa9deedc8451f0c54e84d6ac3c2bdc1807688989
CustomerRepositoryList relied on created at time for the output sorting,
however the granularity of the timer may cause multiple customers
having the same "created at" time.
Add a sleep so that every customer does get a unique time.
Change-Id: If2923174f304fa5f41260d500f6139e3fa7c3ba5
