Complete the ConfigKit resource migration

internal/configuration/load_test.go

@@ -360,6 +360,22 @@ func TestLoadRejectsMalformedHeadersAndLegacyResourceMappings(t *testing.T) {
 	}
 }
 
+func TestNestedConfigRemainsApplicationData(t *testing.T) {
+	state, err := load(mapping("nested config", map[string]any{
+		"config": map[string]any{},
+		"profiles": []any{map[string]any{"id": "example", "extra_params": map[string]any{
+			"config": map[string]any{"imports": "provider data"},
+		}}},
+	}), nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	profile, err := state.GetProfile(context.Background(), "example")
+	if err != nil || profile.ResolvedTarget.ExtraParams["config"].(map[string]any)["imports"] != "provider data" {
+		t.Fatalf("nested application data = %+v, %v", profile, err)
+	}
+}
+
 func TestLoadConsumesAcceptedUnderlayVersionAndValidatesHeaderlessPayload(t *testing.T) {
 	underlay := mapping("declared underlay", map[string]any{
 		"version": int64(2),