code: @Override
      public List<NoDelay> buildConstraint(BtrPlaceTree t, List<BtrpOperand> args) {
          if (checkConformance(t, args)) {
              @SuppressWarnings("unchecked")
              List<VM> s = (List<VM>) params[0].transform(this, t, args.get(0));
              return s != null ? NoDelay.newNoDelay(s) : Collections.emptyList();
          }
          return Collections.emptyList();
      }
docs: Build an online constraint.
  
  @param args must be 1 set of vms. The set must not be empty
  @return a constraint