code: OmemoCachedDeviceList cleanUpDeviceList(OmemoDevice userDevice) {
          OmemoCachedDeviceList cachedDeviceList;
  
          // Delete stale devices if allowed and necessary
          if (OmemoConfiguration.getDeleteStaleDevices()) {
              cachedDeviceList = deleteStaleDevices(userDevice);
          } else {
              cachedDeviceList = getOmemoStoreBackend().loadCachedDeviceList(userDevice);
          }
  
  
          // Add back our device if necessary
          if (!cachedDeviceList.getActiveDevices().contains(userDevice.getDeviceId())) {
              cachedDeviceList.addDevice(userDevice.getDeviceId());
          }
  
          getOmemoStoreBackend().storeCachedDeviceList(userDevice, userDevice.getJid(), cachedDeviceList);
          return cachedDeviceList;
      }
docs: Add our load the deviceList of the user from cache, delete stale devices if needed, add the users device
  back if necessary, store the refurbished list in cache and return it.
  
  @param userDevice
  @return