code: public void add(VMTransitionBuilder b) {
          Map<VMState, VMTransitionBuilder> m = vmAMB2.get(b.getDestinationState());
          for (VMState src : b.getSourceStates()) {
              m.put(src, b);
          }
      }
docs: Add a builder for a VM.
  Every builder that supports the same transition will be replaced.
  
  @param b the builder to add