fix(odata-client): route Headers microflow to its own slot (#728, CE6808)

Follow-up to 045ee6f23. That fix mapped BOTH the "Configuration microflow"
and "Headers microflow" MDL keywords to the configuration slot, so on 11.10+ a
`HeadersMicroflow:` reference was written to ConfigurationEntityMicroflow —
Studio Pro then demanded a System.ConsumedODataConfiguration return type and
raised CE6808 against a microflow that (correctly) returns a list of
System.HttpHeader.

Mendix stores the two as distinct fields on 11.10+: ConfigurationEntity-
Microflow vs HeaderListMicroflow (before 11.10 they shared ConfigurationMicroflow
and were distinguished by return type). Track them as separate model fields:

- model gains a HeadersMicroflow field + ODataHeadersMicroflowBSONKey (11.10+ →
  HeaderListMicroflow, else ConfigurationMicroflow).
- AST/visitor route the `HeadersMicroflow` keyword to the new field; the
  executor, both writers, and both read paths carry it through; DESCRIBE emits
  the matching keyword.

Verified end-to-end on the OData doctype example (11.12): HeadersConfigAPI now
stores HeaderListMicroflow, DESCRIBE round-trips `HeadersMicroflow:`, and CE6808
is gone. Combined with the capability-default revert, the doctype script's OData
errors drop from 36 to 9 (the remaining 9 are a separate published-service issue).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ako

mdl-examples/bug-tests/728-odata-config-microflow-version-key.mdl

@@ -31,16 +31,35 @@
 
 create module BugTest728;
 
-create microflow BugTest728.ConfigureRequest () returns void
+create microflow BugTest728.ConfigureRequest () returns System.ConsumedODataConfiguration
 begin
+  $Config = create System.ConsumedODataConfiguration;
+  return $Config;
+end;
+
+create microflow BugTest728.SetHeaders () returns list of System.HttpHeader
+begin
+  $Headers = create list of System.HttpHeader;
+  return $Headers;
 end;
 /
 
+-- Configuration microflow → BSON ConfigurationEntityMicroflow (11.10+).
 create odata client BugTest728.ConfigSvc (
   ODataVersion: OData4,
   MetadataUrl: 'https://example.com/odata/$metadata',
   Timeout: 300,
   ConfigurationMicroflow: microflow BugTest728.ConfigureRequest
 );
 
+-- Headers microflow → BSON HeaderListMicroflow (11.10+), a DIFFERENT slot.
+-- Storing it in the configuration slot would trigger CE6808.
+create odata client BugTest728.HeadersSvc (
+  ODataVersion: OData4,
+  MetadataUrl: 'https://example.com/odata/$metadata',
+  Timeout: 300,
+  HeadersMicroflow: microflow BugTest728.SetHeaders
+);
+
 describe odata client BugTest728.ConfigSvc;
+describe odata client BugTest728.HeadersSvc;

mdl/ast/ast_odata.go

@@ -26,11 +26,13 @@ type CreateODataClientStmt struct {
 	HttpPassword      string // Mendix expression for password
 	ClientCertificate string
 
-	// Microflow reference. Both `ConfigurationMicroflow` and the legacy
-	// `HeadersMicroflow` MDL keywords write to this same field; Studio
-	// Pro distinguishes the two dropdown options by the microflow's
-	// return type, not by BSON field.
-	ConfigurationMicroflow string // microflow Module.ConfigureMF or Module.SetHeadersMF
+	// Microflow references. `ConfigurationMicroflow` (returns
+	// System.ConsumedODataConfiguration) and `HeadersMicroflow` (returns a list
+	// of System.HttpHeader) are distinct storage slots on Mendix >= 11.10, so
+	// they are tracked separately (writing one into the other's slot triggers
+	// CE6808/CE6816).
+	ConfigurationMicroflow string // microflow Module.ConfigureMF
+	HeadersMicroflow       string // microflow Module.SetHeadersMF
 	ErrorHandlingMicroflow string // microflow Module.HandleErrorMF
 
 	// Proxy constant references

mdl/backend/modelsdk/integration_read.go

@@ -46,14 +46,17 @@ func (b *Backend) ListConsumedODataServices() ([]*model.ConsumedODataService, er
 			EndpointId:        g.EndpointId(),
 			CatalogUrl:        g.CatalogUrl(),
 			EnvironmentType:   g.EnvironmentType(),
-			// The config-microflow field was renamed across versions (issue #728);
-			// coalesce every historical storage key so DESCRIBE round-trips a
-			// service authored by any Mendix version.
+			// The microflow storage fields were renamed/split across versions
+			// (issue #728). Config slot: ConfigurationEntityMicroflow (11.10+) or
+			// the pre-11.10 single slot (ConfigurationMicroflow / ancient
+			// HeadersMicroflow). Headers slot is only distinct on 11.10+
+			// (HeaderListMicroflow). Coalesce so DESCRIBE round-trips any version.
 			ConfigurationMicroflow: firstNonEmpty(
-				g.ConfigurationEntityMicroflowQualifiedName(), // >= 11.10
-				g.ConfigurationMicroflowQualifiedName(),       // 10.12 – 11.10
-				g.HeadersMicroflowQualifiedName(),             // < 10.12
+				g.ConfigurationEntityMicroflowQualifiedName(), // >= 11.10 config
+				g.ConfigurationMicroflowQualifiedName(),       // 10.12 – 11.10 (single slot)
+				g.HeadersMicroflowQualifiedName(),             // < 10.12 (single slot)
 			),
+			HeadersMicroflow:       g.HeaderListMicroflowQualifiedName(), // >= 11.10 headers
 			ErrorHandlingMicroflow: g.ErrorHandlingMicroflowQualifiedName(),
 			ProxyHost:              g.ProxyHostQualifiedName(),
 			ProxyPort:              g.ProxyPortQualifiedName(),

mdl/backend/modelsdk/odata_write.go

@@ -52,7 +52,7 @@ func (b *Backend) CreateConsumedODataService(svc *model.ConsumedODataService) er
 		svc.ID = model.ID(mmpr.GenerateID())
 	}
 	svc.TypeName = "Rest$ConsumedODataService"
-	contents, err := (&codec.Encoder{}).Encode(consumedODataServiceToGen(svc, b.configMicroflowKey()))
+	contents, err := b.encodeConsumedODataService(svc)
 	if err != nil {
 		return fmt.Errorf("CreateConsumedODataService: encode: %w", err)
 	}
@@ -66,7 +66,7 @@ func (b *Backend) UpdateConsumedODataService(svc *model.ConsumedODataService) er
 	if b.writer == nil {
 		return fmt.Errorf("UpdateConsumedODataService: not connected for writing")
 	}
-	contents, err := (&codec.Encoder{}).Encode(consumedODataServiceToGen(svc, b.configMicroflowKey()))
+	contents, err := b.encodeConsumedODataService(svc)
 	if err != nil {
 		return fmt.Errorf("UpdateConsumedODataService: encode: %w", err)
 	}
@@ -80,17 +80,25 @@ func (b *Backend) DeleteConsumedODataService(id model.ID) error {
 	return b.writer.DeleteUnit(string(id))
 }
 
-// configMicroflowKey returns the version-appropriate BSON field name for the
-// consumed OData service's configuration microflow (issue #728). Defaults to the
-// pre-11.10 key when the project version is unknown.
-func (b *Backend) configMicroflowKey() string {
+// encodeConsumedODataService serializes the service with version-appropriate
+// microflow BSON keys.
+func (b *Backend) encodeConsumedODataService(svc *model.ConsumedODataService) ([]byte, error) {
+	configKey, headersKey := b.microflowKeys()
+	return (&codec.Encoder{}).Encode(consumedODataServiceToGen(svc, configKey, headersKey))
+}
+
+// microflowKeys returns the version-appropriate BSON field names for the
+// consumed OData service's configuration and headers microflows (issue #728).
+// Defaults to the pre-11.10 keys when the project version is unknown.
+func (b *Backend) microflowKeys() (configKey, headersKey string) {
 	if pv := b.ProjectVersion(); pv != nil {
-		return model.ODataConfigMicroflowBSONKey(pv.MajorVersion, pv.MinorVersion)
+		return model.ODataConfigMicroflowBSONKey(pv.MajorVersion, pv.MinorVersion),
+			model.ODataHeadersMicroflowBSONKey(pv.MajorVersion, pv.MinorVersion)
 	}
-	return "ConfigurationMicroflow"
+	return "ConfigurationMicroflow", "ConfigurationMicroflow"
 }
 
-func consumedODataServiceToGen(svc *model.ConsumedODataService, configMicroflowKey string) element.Element {
+func consumedODataServiceToGen(svc *model.ConsumedODataService, configMicroflowKey, headersMicroflowKey string) element.Element {
 	g := newElem("Rest$ConsumedODataService", string(svc.ID))
 	addStr(g, "Name", svc.Name)
 	addStr(g, "Documentation", svc.Documentation)
@@ -115,6 +123,7 @@ func consumedODataServiceToGen(svc *model.ConsumedODataService, configMicroflowK
 	// Optional by-name / constant references — only emitted when set, matching the
 	// legacy writer (Studio Pro omits empties).
 	addStrIf(g, configMicroflowKey, svc.ConfigurationMicroflow)
+	addStrIf(g, headersMicroflowKey, svc.HeadersMicroflow)
 	addStrIf(g, "ErrorHandlingMicroflow", svc.ErrorHandlingMicroflow)
 	addStrIf(g, "ProxyHost", svc.ProxyHost)
 	addStrIf(g, "ProxyPort", svc.ProxyPort)

mdl/backend/modelsdk/odata_write_test.go

@@ -198,7 +198,7 @@ func TestConsumedODataServiceToGen_ConfigMicroflowKey(t *testing.T) {
 		{"ConfigurationEntityMicroflow", "ConfigurationEntityMicroflow", "ConfigurationMicroflow"},
 		{"ConfigurationMicroflow", "ConfigurationMicroflow", "ConfigurationEntityMicroflow"},
 	} {
-		raw, err := (&codec.Encoder{}).Encode(consumedODataServiceToGen(svc, tc.key))
+		raw, err := (&codec.Encoder{}).Encode(consumedODataServiceToGen(svc, tc.key, "HeaderListMicroflow"))
 		if err != nil {
 			t.Fatalf("encode(%s): %v", tc.key, err)
 		}

mdl/executor/cmd_odata.go

@@ -174,14 +174,15 @@ func outputConsumedODataServiceMDL(ctx *ExecContext, svc *model.ConsumedODataSer
 		}
 	}
 
-	// Microflow reference. Both the "Configuration microflow" and
-	// "Headers microflow" Studio Pro dropdown options share a single
-	// BSON field — DESCRIBE outputs `ConfigurationMicroflow` for both;
-	// the source MDL keyword (`ConfigurationMicroflow` /
-	// `HeadersMicroflow`) is purely a hint to the reader.
+	// Microflow references. The "Configuration microflow" and "Headers
+	// microflow" dropdown options are distinct storage slots (Mendix >= 11.10),
+	// so DESCRIBE emits the matching MDL keyword for each.
 	if svc.ConfigurationMicroflow != "" {
 		props = append(props, fmt.Sprintf("  ConfigurationMicroflow: microflow %s", svc.ConfigurationMicroflow))
 	}
+	if svc.HeadersMicroflow != "" {
+		props = append(props, fmt.Sprintf("  HeadersMicroflow: microflow %s", svc.HeadersMicroflow))
+	}
 	if svc.ErrorHandlingMicroflow != "" {
 		props = append(props, fmt.Sprintf("  ErrorHandlingMicroflow: microflow %s", svc.ErrorHandlingMicroflow))
 	}
@@ -953,6 +954,9 @@ func createODataClient(ctx *ExecContext, stmt *ast.CreateODataClientStmt) error
 					if stmt.ConfigurationMicroflow != "" {
 						svc.ConfigurationMicroflow = extractMicroflowRef(stmt.ConfigurationMicroflow)
 					}
+					if stmt.HeadersMicroflow != "" {
+						svc.HeadersMicroflow = extractMicroflowRef(stmt.HeadersMicroflow)
+					}
 					if stmt.ErrorHandlingMicroflow != "" {
 						svc.ErrorHandlingMicroflow = extractMicroflowRef(stmt.ErrorHandlingMicroflow)
 					}
@@ -1040,6 +1044,7 @@ func createODataClient(ctx *ExecContext, stmt *ast.CreateODataClientStmt) error
 		ProxyType:              stmt.ProxyType,
 		Description:            stmt.Description,
 		ConfigurationMicroflow: extractMicroflowRef(stmt.ConfigurationMicroflow),
+		HeadersMicroflow:       extractMicroflowRef(stmt.HeadersMicroflow),
 		ErrorHandlingMicroflow: extractMicroflowRef(stmt.ErrorHandlingMicroflow),
 		ProxyHost:              stmt.ProxyHost,
 		ProxyPort:              stmt.ProxyPort,
@@ -1189,9 +1194,10 @@ func alterODataClient(ctx *ExecContext, stmt *ast.AlterODataClientStmt) error {
 						svc.HttpConfiguration = &model.HttpConfiguration{}
 					}
 					svc.HttpConfiguration.ClientCertificate = strVal
-				case "configurationmicroflow", "headersmicroflow":
-					// Both MDL keywords write to the same BSON field.
+				case "configurationmicroflow":
 					svc.ConfigurationMicroflow = extractMicroflowRef(strVal)
+				case "headersmicroflow":
+					svc.HeadersMicroflow = extractMicroflowRef(strVal)
 				case "errorhandlingmicroflow":
 					svc.ErrorHandlingMicroflow = extractMicroflowRef(strVal)
 				case "proxyhost":

mdl/executor/cmd_odata_mock_test.go

@@ -665,11 +665,13 @@ func TestCreateODataClient_HeadersMicroflow(t *testing.T) {
 	if captured == nil {
 		t.Fatal("CreateConsumedODataService was not called")
 	}
-	// Both `HeadersMicroflow` and `ConfigurationMicroflow` MDL keywords
-	// now map to the same model field (and the same Studio Pro BSON
-	// field). Studio Pro picks the dropdown label by the microflow's
-	// return type, not by which field carries the reference.
-	if captured.ConfigurationMicroflow != "MyModule.SetHeaders" {
-		t.Errorf("ConfigurationMicroflow = %q, want %q", captured.ConfigurationMicroflow, "MyModule.SetHeaders")
+	// The `HeadersMicroflow` keyword maps to the distinct HeadersMicroflow
+	// model field (Studio Pro's HeaderListMicroflow slot on 11.10+), NOT the
+	// configuration slot — conflating them triggers CE6808 (issue #728).
+	if captured.HeadersMicroflow != "MyModule.SetHeaders" {
+		t.Errorf("HeadersMicroflow = %q, want %q", captured.HeadersMicroflow, "MyModule.SetHeaders")
+	}
+	if captured.ConfigurationMicroflow != "" {
+		t.Errorf("ConfigurationMicroflow = %q, want empty (headers keyword must not populate the config slot)", captured.ConfigurationMicroflow)
 	}
 }

mdl/visitor/visitor_odata.go

@@ -49,17 +49,15 @@ func (b *Builder) ExitCreateODataClientStatement(ctx *parser.CreateODataClientSt
 			stmt.HttpPassword = value
 		case "clientcertificate":
 			stmt.ClientCertificate = value
-		case "configurationmicroflow", "headersmicroflow":
-			// Both MDL property names map to the same BSON field
-			// `ConfigurationMicroflow`. Studio Pro distinguishes the
-			// "Configuration microflow" and "Headers microflow"
-			// dropdown options by the microflow's return type:
-			//   - returns System.ConsumedODataConfiguration -> Config
-			//   - returns list of System.HttpHeader         -> Headers
-			// The `HeadersMicroflow` keyword stays for ergonomic MDL
-			// (so the example MDL can self-document which signature
-			// the referenced microflow is expected to have).
+		case "configurationmicroflow":
+			// "Configuration microflow" — returns System.ConsumedODataConfiguration.
 			stmt.ConfigurationMicroflow = value
+		case "headersmicroflow":
+			// "Headers microflow" — returns list of System.HttpHeader. A distinct
+			// storage slot from the configuration microflow on Mendix >= 11.10
+			// (HeaderListMicroflow vs ConfigurationEntityMicroflow); conflating
+			// them triggers CE6808.
+			stmt.HeadersMicroflow = value
 		case "errorhandlingmicroflow":
 			stmt.ErrorHandlingMicroflow = value
 		case "proxyhost":

model/odata_config_microflow_test.go

@@ -26,3 +26,25 @@ func TestODataConfigMicroflowBSONKey(t *testing.T) {
 		}
 	}
 }
+
+// TestODataHeadersMicroflowBSONKey guards the headers-microflow slot (issue
+// #728): distinct from the configuration slot on 11.10+ (HeaderListMicroflow);
+// before 11.10 both shared ConfigurationMicroflow. Writing a headers microflow
+// into the configuration slot triggers CE6808.
+func TestODataHeadersMicroflowBSONKey(t *testing.T) {
+	cases := []struct {
+		major, minor int
+		want         string
+	}{
+		{11, 9, "ConfigurationMicroflow"}, // pre-11.10 shared slot
+		{11, 10, "HeaderListMicroflow"},   // split introduced
+		{11, 11, "HeaderListMicroflow"},   // reporter's version
+		{11, 12, "HeaderListMicroflow"},   // doctype project
+		{12, 0, "HeaderListMicroflow"},
+	}
+	for _, c := range cases {
+		if got := ODataHeadersMicroflowBSONKey(c.major, c.minor); got != c.want {
+			t.Errorf("ODataHeadersMicroflowBSONKey(%d.%d) = %q, want %q", c.major, c.minor, got, c.want)
+		}
+	}
+}

model/types.go

@@ -327,6 +327,12 @@ type ConsumedODataService struct {
 	// only" (issue #728). The MDL `HeadersMicroflow` keyword is an alias that
 	// writes to this same field.
 	ConfigurationMicroflow string `json:"configurationMicroflow,omitempty"` // BSON: version-gated, see ODataConfigMicroflowBSONKey
+	// HeadersMicroflow is the "Headers microflow" dropdown option (returns a
+	// list of System.HttpHeader). It is a DIFFERENT storage slot from the
+	// configuration microflow on Mendix >= 11.10 (see ODataHeadersMicroflowBSONKey):
+	// mapping it to the configuration slot makes Studio Pro demand a
+	// System.ConsumedODataConfiguration return type (CE6808).
+	HeadersMicroflow       string `json:"headersMicroflow,omitempty"`       // BSON: version-gated, see ODataHeadersMicroflowBSONKey
 	ErrorHandlingMicroflow string `json:"errorHandlingMicroflow,omitempty"` // BSON: ErrorHandlingMicroflow
 
 	// Proxy constant references (BY_NAME to Constants$Constant)
@@ -370,6 +376,19 @@ func ODataConfigMicroflowBSONKeys() []string {
 	return []string{"ConfigurationEntityMicroflow", "ConfigurationMicroflow", "HeadersMicroflow"}
 }
 
+// ODataHeadersMicroflowBSONKey returns the BSON storage field for a consumed
+// OData service's "Headers microflow" (returns list of System.HttpHeader). On
+// Mendix >= 11.10 this is a distinct slot, HeaderListMicroflow; before 11.10 the
+// configuration and headers microflows shared the single ConfigurationMicroflow
+// field (Studio Pro distinguished them by the microflow's return type). Writing
+// a headers microflow into the configuration slot triggers CE6808 (issue #728).
+func ODataHeadersMicroflowBSONKey(major, minor int) string {
+	if major > 11 || (major == 11 && minor >= 10) {
+		return "HeaderListMicroflow"
+	}
+	return "ConfigurationMicroflow"
+}
+
 // HttpConfiguration represents the HTTP transport configuration (Microflows$HttpConfiguration).
 type HttpConfiguration struct {
 	BaseElement