Updates state migrator to follow HashiCorp recommendations

resource_alks_iamrole.go

@@ -227,9 +227,24 @@ func populateResourceDataFromRole(role *alks.IamRoleResponse, d *schema.Resource
 func migrateState(version int, state *terraform.InstanceState, meta interface{}) (*terraform.InstanceState, error) {
 	switch version {
 	case 0:
-		state.Attributes["enable_alks_access"] = "false"
-		return state, nil
+		log.Println("[INFO] Found Instance State v0, migrating to v1")
+		return migrateV0toV1(state)
 	default:
-		return state, fmt.Errorf("Unrecognized version '%q' in schema for instance of ALKS IAM role", version)
+		return state, fmt.Errorf("Unrecognized version '%d' in schema for instance of ALKS IAM role '%s'", version, state.Attributes["name"])
+	}
+}
+
+func migrateV0toV1(state *terraform.InstanceState) (*terraform.InstanceState, error) {
+	if state.Empty() {
+		log.Println("[DEBUG] Empty InstanceState, nothing to migrate")
+		return state, nil
 	}
+
+	if _, ok := state.Attributes["enable_alks_access"]; !ok {
+		log.Printf("[DEBUG] Attributes before migration: %#v", state.Attributes)
+		state.Attributes["enable_alks_access"] = "false"
+		log.Printf("[DEBUG] Attributes after migration: %#v", state.Attributes)
+	}
+
+	return state, nil
 }