Automatic Nested Mapping Support

[talehkarimov]

📝 Description

Implement automatic nested mapping support in CleanMapper to map complex object graphs without requiring manual mapping calls for each nested property or collection.

✅ Acceptance Criteria

• When mapping a class that contains nested class properties, CleanMapper automatically maps those nested objects if mappings exist for their types.
• When mapping a class that contains collections of nested objects (e.g. List), CleanMapper automatically maps each item if mappings exist for their element types.
• The feature respects existing configured mappings and throws a clear exception if a nested mapping is missing.
• Unit tests cover
  • Nested object mapping
  • Collections of nested objects mapping
  • Scenarios with missing nested mappings

🔧 Implementation Notes

• Extend MappingConfiguration.CreateMap to:
  • Detect destination properties that are complex types or collections.
  • For complex types, call existing mappings recursively.
  • For collections, generate mapping expressions for each item.
• Ensure no runtime reflection is used during mapping execution.

⚠️ Potential Challenges

• Handling cyclical references (to avoid infinite recursion).
• Distinguishing between primitive types, strings, collections, and complex classes during expression tree generation.