Add reference contracts to extractor metadata

internal/modules/input/seriatim/config_test.go

@@ -221,6 +221,8 @@ func (fakeExtractor) ArtifactType() string { return "fake" }
 
 func (fakeExtractor) SchemaVersion() string { return "v1" }
 
+func (fakeExtractor) ReferenceSlots() []contracts.ReferenceSlot { return nil }
+
 func (fakeExtractor) Validators() []contracts.Validator { return nil }
 
 func (fakeExtractor) Extract(ctx context.Context, req contracts.ExtractionRequest) (contracts.ExtractionResult, error) {

internal/modules/input/seriatim/runner_test.go

@@ -186,6 +186,10 @@ func (e *runnerSeriatimExtractor) SchemaVersion() string {
 	return "v1"
 }
 
+func (e *runnerSeriatimExtractor) ReferenceSlots() []contracts.ReferenceSlot {
+	return nil
+}
+
 func (e *runnerSeriatimExtractor) Validators() []contracts.Validator {
 	return nil
 }