**Features**
- Rewrite TreeSerializer, drop support for native python ElementTree
([1032](https://github.com/tefra/xsdata/pull/1032))
- Validate fields fixed values ([1013](https://github.com/tefra/xsdata/pull/1013))
- Detect optional fields in dict mapper
- Refactor typing annotations analyze process
- Generate ForwardRef() instead of Type[]
**Fixes**
- Allow soap client config subclassing
([1010](https://github.com/tefra/xsdata/pull/1010))
- Avoid recursive error on nested group references
([1016](https://github.com/tefra/xsdata/pull/1016))
- Add warning for same module designation
([1018](https://github.com/tefra/xsdata/pull/1018))