docs: protected boolean shouldDropUpMessage(@SuppressWarnings("UnusedParameters") Message msg, Address sender) {
          if(discard_all && !sender.equals(localAddress()))
              return true;
  
          if(ignoredMembers.contains(sender)) {
              if(log.isTraceEnabled())
                  log.trace(localAddress + ": dropping message from " + sender);
              num_up++;
              return true;
          }
  
          if(up > 0) {
              double r=Math.random();
              if(r < up) {
                  if(excludeItself && sender.equals(localAddress())) {
                      if(log.isTraceEnabled())
                          log.trace("excluding myself");
                  }
                  else {
                      if(log.isTraceEnabled())
                          log.trace(localAddress + ": dropping message from " + sender);
                      num_up++;
                      return true;
                  }
              }
          }
          return false;
      }