fix: don't collect constructors of private classes (#253)

Author: devmil

lib/src/analyze/api_relevant_elements_collector.dart

@@ -204,6 +204,10 @@ class APIRelevantElementsCollector extends RecursiveElementVisitor2<void> {
       if (element.enclosingElement2 is EnumElement2) {
         return false;
       }
+      // constructors of private classes aren't collected
+      if (element.enclosingElement2.isPrivate) {
+        return false;
+      }
     }
     // don't collect any override -> already part of the source
     if (element is Annotatable &&

test/integration_tests/diff/native_test.dart

@@ -40,5 +40,26 @@ void main() {
         expect(breakingChanges, []);
       });
     });
+
+    group('objective_c', () {
+      late final PackageApi objcApi;
+      final refObjc = '0924cb0e80ed6ac39298363fabe0916808a4a1fe';
+
+      setUp(() async {
+        final objcRetriever = GitPackageApiRetriever(
+          gitUrl,
+          refObjc,
+          relativePackagePath: 'pkgs/objective_c',
+        );
+        objcApi = await objcRetriever.retrieve();
+      });
+
+      test('_FinalizablePointer should not be leaked in the public API',
+          () async {
+        final hasFinalizablePointer = objcApi.interfaceDeclarations
+            .any((id) => id.name == '_FinalizablePointer');
+        expect(hasFinalizablePointer, isFalse);
+      });
+    });
   });
 }