Serialization/Deserialization Debugger

Help me debug serialization/deserialization issues.

**Format:** {{FORMAT}}
**Language:** {{LANGUAGE}}
**Library:** {{LIBRARY}}

**Data class/structure:**
```{{LANGUAGE}}
{{DATA_CLASS}}
```

**Serialization code:**
```{{LANGUAGE}}
{{SERIALIZATION_CODE}}
```

**Input data:**
```
{{INPUT_DATA}}
```

**Error or incorrect result:**
```
{{ERROR}}
```

**Expected result:** {{EXPECTED}}

Please provide:
1. **Format Validation**: Validate input data format
2. **Schema Mismatch**: Check data class vs data mismatch
3. **Null Handling**: Check null/missing field handling
4. **Type Coercion**: Identify type conversion issues
5. **Fixed Code**: Corrected serialization code
6. **Annotation/Attributes**: Proper serialization annotations
7. **Edge Cases**: Handle special values and edge cases
8. **Versioning**: Handle schema versioning