fix #590: rewrite Level 9.1 call-external-action to use TripPin schema

The original Level 9.1 created a microflow `OdTest.ACT_CallExternalAction`
that called `OdTest.SalesforceAPI.GetAccounts(...)` and
`OdTest.SalesforceAPI.NotifyUpdate(...)`. SalesforceAPI's MetadataUrl is a
placeholder that doesn't return $metadata, so the ConsumedODataService BSON
is written with an empty `Metadata` cache. Studio Pro's project checker
then resolves the Name fields against an empty schema, gets null, and the
checker aborts with a NullReferenceException in
`Mendix.Modeler.Integration.CallExternalAction.get_SchemaAction()` →
`ExternalActionParameterMapping.get_SchemaParameter()`. The crash blocks
all in-IDE error reporting, not just for this microflow.

Move the microflow definition to a new Level 10.4.1, right after the
TripPin client is created (Level 10.1) and its $metadata is actually
cached. Use unbound TripPin entries `GetNearestAirport` (Function with
lat/lon parameters and a Trippin.Airport return) and `ResetDataSource`
(parameterless Action) so both the parameter-mapping and the
`on error continue` variants are still demonstrated.

The microflow stays in `OdTest` so `show external actions in OdTest`
(Level 9.2) still returns a row. The existing drop in Level 8.8a already
runs before Level 8.8c (TripPin client drop), so cleanup order is correct.

Issue #590 separately documents the upstream Studio Pro robustness gap
(`SchemaAction` should null-check instead of NREing) so it can be
escalated to Mendix support.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: ako

mdl-examples/doctype-tests/10-odata-examples.mdl

@@ -378,16 +378,15 @@ revoke access on odata service OdTest.CustomerAPI from OdTest.user;
 -- LEVEL 9: EXTERNAL ACTION CALLS IN MICROFLOWS
 -- ############################################################################
 
-/**
- * Level 9.1: Call an external action with parameters and result variable
- */
-create microflow OdTest.ACT_CallExternalAction() returns boolean
-begin
-    $Result = call external action OdTest.SalesforceAPI.GetAccounts(status = 'active', Region = $SelectedRegion);
-    call external action OdTest.SalesforceAPI.NotifyUpdate(AccountId = $AccountId) on error continue;
-    return true;
-end;
-/
+-- Level 9.1: Call an external action — see Level 10.4.1 below.
+--
+-- The microflow is created after Level 10.1 because Studio Pro resolves
+-- `call external action` Name fields against the cached $metadata schema of
+-- the ConsumedODataService. SalesforceAPI's MetadataUrl is a placeholder
+-- that doesn't actually return $metadata, so its cache is empty and any
+-- action call against it would crash Studio Pro's project checker with a
+-- NullReferenceException in CallExternalAction.SchemaAction (see mxcli#590).
+-- TripPin has reachable metadata, so its actions resolve correctly.
 
 /**
  * Level 9.2: Show external actions discovered from microflow usage
@@ -462,14 +461,31 @@ create or modify external entities from TripPinClient."TripPinApiClient"
   into TripPinClient;
 /
 
+/**
+ * Level 10.4.1: Demonstrate `call external action` against TripPin schema
+ * actions. Both ResetDataSource (no parameters) and GetNearestAirport
+ * (parameterised with a return variable) are unbound entries in TripPin's
+ * cached $metadata, so Studio Pro's project checker resolves SchemaAction
+ * correctly. The microflow lives in OdTest to keep `show external actions
+ * in OdTest` (Level 9.2) returning a row, but references the TripPin client.
+ */
+create microflow OdTest.ACT_CallExternalAction() returns boolean
+begin
+    $Airport = call external action TripPinClient."TripPinApiClient".GetNearestAirport(lat = 47.6062, lon = -122.3321);
+    call external action TripPinClient."TripPinApiClient".ResetDataSource() on error continue;
+    return true;
+end;
+/
+
 -- ############################################################################
 -- LEVEL 8.8: DROP (cleanup)
 -- ############################################################################
 
 /**
- * Level 8.8a: Drop objects that reference SalesforceAPI before dropping the client.
- * OdTest.ACT_CallExternalAction calls SalesforceAPI actions; OdTest.RemoteAccount
- * is an external entity backed by SalesforceAPI — both must be removed first.
+ * Level 8.8a: Drop objects that reference OData clients before dropping the
+ * clients themselves. OdTest.ACT_CallExternalAction (created in Level 10.4.1)
+ * calls TripPin actions, and OdTest.RemoteAccount is an external entity
+ * backed by SalesforceAPI — both must be removed first.
  */
 drop microflow OdTest.ACT_CallExternalAction;
 /