private static Set<TenantName> toTenants(HttpResponse<byte[]> response) {
        Set<TenantName> tenants = new HashSet<>();
        toInspector(response).traverse((ArrayTraverser) (___, entryObject) ->
                tenants.add(TenantName.from(entryObject.field("tenant").asString())));
        return tenants;
    }
Returns the "message" element contained in the JSON formatted response.
hosted-api/src/main/java/ai/vespa/hosted/api/ControllerHttpClient.java