- public Iterable<ITmfStateSystem> getStateSystems() {
- List<ITmfStateSystem> list = new LinkedList<>();
- list.add(totalsModule.getStateSystem());
- list.add(eventTypesModule.getStateSystem());
+ public @NonNull Iterable<@NonNull ITmfStateSystem> getStateSystems() {
+ List<@NonNull ITmfStateSystem> list = new LinkedList<>();
+ ITmfStateSystem totalsStateSystem = totalsModule.getStateSystem();
+ if (totalsStateSystem != null) {
+ list.add(totalsStateSystem);
+ }
+ ITmfStateSystem eventTypesStateSystem = eventTypesModule.getStateSystem();
+ if (eventTypesStateSystem != null) {
+ list.add(eventTypesStateSystem);
+ }