private IEnumerable <RhinoTestCase> GetByPlan(string issueKey)
        {
            // parse into JToken
            var jsonObject = jiraClient.Get(issueKey).AsJObject();

            if (jsonObject == default)
            {
                return(Array.Empty <RhinoTestCase>());
            }

            // find & validate test cases
            var customField = jiraClient.GetCustomField(TestPlanSchema);
            var onTestCases = jsonObject.SelectToken($"..{customField}");

            Logger?.DebugFormat($"Get-Tests -By [{AtlassianCapabilities.PlanType}] = {onTestCases.Count()}");

            // iterate & load tests
            var testCases = new List <RhinoTestCase>();

            foreach (var onTestCase in onTestCases)
            {
                testCases.AddRange(GetOne($"{onTestCase}"));
            }
            return(testCases);
        }