static void Main(string[] args)
        {
            var apiKey     = "API-XXXXXXXXXXXXXXXXXXXXXXXXXX";
            var octopusURL = "https://octopus.url";

            var endpoint   = new OctopusServerEndpoint(octopusURL, apiKey);
            var client     = new OctopusClient(endpoint);
            var repository = new OctopusRepository(endpoint);

            var actionTemplates = repository.ActionTemplates.GetAll();

            foreach (var actionTemplate in actionTemplates)
            {
                var usages         = client.Get <ActionTemplateUsageResource[]>(actionTemplate.Links["Usage"]);
                var usagesToUpdate = usages.Where(u => u.Version != actionTemplate.Version.ToString());

                if (!usagesToUpdate.Any())
                {
                    continue;
                }

                var actionsByProcessId   = usagesToUpdate.GroupBy(u => u.DeploymentProcessId);
                var actionIdsByProcessId = actionsByProcessId.ToDictionary(g => g.Key, g => g.Select(u => u.ActionId).ToArray());

                var actionUpdate = new ActionsUpdateResource();
                actionUpdate.Version = actionTemplate.Version;
                actionUpdate.ActionIdsByProcessId = actionIdsByProcessId;
                repository.ActionTemplates.UpdateActions(actionTemplate, actionUpdate);
            }
        }