Add tenantId to identify management group

Author: Madhumitha Raveendar (from Dev Box)

specification/cost-management/resource-manager/Microsoft.CostManagement/CostManagement/examples/2026-06-01/BenefitRecommendationsByBillingAccountForManagementGroup.json

@@ -49,6 +49,7 @@
                 "wastageCost": 0.035
               },
               "managementGroupId": "/providers/Microsoft.Management/managementGroups/00000000-0000-0000-0000-000000000001",
+              "tenantId": "00000000-0000-0000-0000-000000000001",
               "scope": "ManagementGroup",
               "term": "P1Y",
               "totalHours": 168,

specification/cost-management/resource-manager/Microsoft.CostManagement/CostManagement/models.tsp

@@ -4502,6 +4502,12 @@ model ManagementGroupScopeBenefitRecommendationProperties
   @visibility(Lifecycle.Read)
   managementGroupId?: string;
 
+  /**
+   * The tenant ID associated with the management group. Populated only when managementGroupId is populated.
+   */
+  @visibility(Lifecycle.Read)
+  tenantId?: string;
+
   /**
    * ManagementGroup benefit scope.
    */

specification/cost-management/resource-manager/Microsoft.CostManagement/CostManagement/stable/2026-06-01/examples/BenefitRecommendationsByBillingAccountForManagementGroup.json

@@ -49,6 +49,7 @@
                 "wastageCost": 0.035
               },
               "managementGroupId": "/providers/Microsoft.Management/managementGroups/00000000-0000-0000-0000-000000000001",
+              "tenantId": "00000000-0000-0000-0000-000000000001",
               "scope": "ManagementGroup",
               "term": "P1Y",
               "totalHours": 168,