eg
```
"impacts": [
            {
              "severity": 3,
              "description": "Searches might return slower than usual. Fewer redundant copies of the data exist on 2 indices [.ds-logslogslogs-2022.03.29-000001, my-index-000001].",
              "impact_areas": [ "search" ]
            }
          ]
```
server/src/test/java/org/elasticsearch/cluster/routing/allocation/ShardsAvailabilityHealthIndicatorServiceTests.java
IndexMetadata.Builder indexMetadataBuilder = new IndexMetadata.Builder(indexName);
                Settings settings = Settings.builder()
                    .put(IndexMetadata.SETTING_PRIORITY, indexNameToPriority.getValue())
                    .put(IndexMetadata.INDEX_NUMBER_OF_SHARDS_SETTING.getKey(), 1)
                    .put(IndexMetadata.INDEX_NUMBER_OF_REPLICAS_SETTING.getKey(), 1)
                    .put(IndexMetadata.SETTING_INDEX_VERSION_CREATED.getKey(), Version.CURRENT)
                    .build();
                indexMetadataBuilder.settings(settings);
                indexMetadataList.add(indexMetadataBuilder.build());
            }
        }
        return indexMetadataList;
    }
    private static ClusterState createClusterStateWith(List<IndexRoutingTable> indexRoutingTables, List<NodeShutdown> nodeShutdowns) {
        return createClusterStateWith(indexRoutingTables, nodeShutdowns, Collections.emptyList());
    }
    private static ClusterState createClusterStateWith(
        List<IndexRoutingTable> indexRoutingTables,
        List<NodeShutdown> nodeShutdowns,
        List<IndexMetadata> indexMetadataList
    ) {
        var routingTableBuilder = RoutingTable.builder();
        for (IndexRoutingTable indexRoutingTable : indexRoutingTables) {
            routingTableBuilder.add(indexRoutingTable);
        }
        var nodesShutdownMetadata = new NodesShutdownMetadata(
            nodeShutdowns.stream()
                .collect(
                    toMap(
                        it -> it.nodeId,