This one is found quite regularly. Replacing brake pads is an easy task performed by many builders. However, quite often I see that the bolts are reinstalled without safety wire. There’s a lot of potential movement of the brake caliper due to the high heat that must be dissipated during braking, so safety wire is important. In the first photo you can see that the bolts have drilled heads.
The second photo shows the correct use of safety wire. It’s also acceptable to use a suitable alternative like Nord-Lock washers underneath the heads of the bolts.