public static List<Event> computeEventDiff(final Params params) {
        final List<Event> events = new ArrayList<>();

        emitPerNodeDiffEvents(createBaselineParams(params), events);
        emitWholeClusterDiffEvent(createBaselineParams(params), events);
        emitDerivedBucketSpaceStatesDiffEvents(params, events);
        return events;
    }
@Test
    void group_down_to_group_down_does_not_emit_new_event() {
        final EventFixture fixture = EventFixture.createForNodes(3)
                .clusterStateBefore("distributor:3 storage:3 .1.s:d")
                .clusterStateAfter("distributor:3 storage:3 .1.s:m")
                .storageNodeReasonBefore(1, NodeStateReason.GROUP_IS_DOWN)
                .storageNodeReasonAfter(1, NodeStateReason.GROUP_IS_DOWN);

        final List<Event> events = fixture.computeEventDiff();
        assertThat(events.size(), equalTo(1));
        // Should not get a group availability event since nothing has changed in this regard
        assertThat(events, hasItem(allOf(
                eventForNode(storageNode(1)),
                nodeEventWithDescription("Altered node state in cluster state from 'D' to 'M'"))));
    }