docs: @Restricted(NoExternalUse.class)
      public DiskSpace markNodeOfflineIfDiskspaceIsTooLow(Computer c) {
          DiskSpace size = (DiskSpace) super.data(c);
          if(size!=null && size.size < getThresholdBytes()) {
          	size.setTriggered(this.getClass(), true);
          	if(getDescriptor().markOffline(c,size)) {
          		LOGGER.warning(Messages.DiskSpaceMonitor_MarkedOffline(c.getDisplayName()));
          	}
          }
          return size;
      }