Update message representation to be more accurate

[mardiros]

Dumping to dict may be error prone on what the object state is really is

since it can be a dict or a validated base model depending on the state
of the validation state.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (495b76d) to head (c4d7a09).

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #28   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           21        21           
  Lines          716       715    -1     
=========================================
- Hits           716       715    -1     

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