In some contexts is unclear why an autoscaling policy decides to request
more resources, i.e. if there's an unassigned shard that remains unassigned
even after adding more resources. It would be help to have more information
around the decisions taken by the deciders so it is easier to understand and
track them.
x-pack/plugin/autoscaling/src/main/java/org/elasticsearch/xpack/autoscaling/storage/ReactiveStorageDeciderService.java
public static final String NAME = "reactive_storage";
    private final DiskThresholdSettings diskThresholdSettings;
    private final AllocationDeciders allocationDeciders;
    public ReactiveStorageDeciderService(Settings settings, ClusterSettings clusterSettings, AllocationDeciders allocationDeciders) {
        this.diskThresholdSettings = new DiskThresholdSettings(settings, clusterSettings);
        this.allocationDeciders = allocationDeciders;
    }
    @Override
    public String name() {
        return NAME;
    }
    @Override
    public List<Setting<?>> deciderSettings() {
        return List.of();
    }
    @Override
    public List<DiscoveryNodeRole> roles() {
        return List.of(
            DiscoveryNodeRole.DATA_ROLE,
            DiscoveryNodeRole.DATA_CONTENT_NODE_ROLE,
            DiscoveryNodeRole.DATA_HOT_NODE_ROLE,
            DiscoveryNodeRole.DATA_WARM_NODE_ROLE,
            DiscoveryNodeRole.DATA_COLD_NODE_ROLE
        );
    }