Handle nested apps.

[sfc-gh-dkurokawa]

Description

Handle nested apps.

Other details good to know for developers

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [x] New Tests
• [ ] This change includes re-generated golden test results
• [ ] This change requires a documentation update