code: @Exported(visibility=2)
  	public List<Cause> getCauses() {
  		List<Cause> r = new ArrayList<>();
          for (Map.Entry<Cause,Integer> entry : causeBag.entrySet()) {
              r.addAll(Collections.nCopies(entry.getValue(), entry.getKey()));
          }
          return Collections.unmodifiableList(r);
  	}
docs: Lists all causes of this build.
  Note that the current implementation does not preserve insertion order of duplicates.
  @return an immutable list;
  to create an action with multiple causes use either of the constructors that support this;
  to append causes retroactively to a build you must create a new {@link CauseAction} and replace the old