DefaultValue attribute on an input object doesn't get applied (#6897)

[DaveRMaltby]

Summary of the changes (Less than 80 chars)

• The fix for #4677 by #4965 took away the [DefaultValue] attribute's effectiveness on a property of type Optional<T>. To avoid the null reference issue that was occuring in #4677, but still allow for [DefaultVaue] attributes to work, in the From() we check if optional.Value != default

Closes #6897

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 70.44%. Comparing base (1865894) to head (8b7203c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6922      +/-   ##
==========================================
- Coverage   70.56%   70.44%   -0.12%     
==========================================
  Files        2597     2583      -14     
  Lines      129007   128371     -636     
==========================================
- Hits        91028    90427     -601     
+ Misses      37979    37944      -35     

Flag	Coverage Δ
unittests	70.44% <100.00%> (-0.12%)	:arrow_down:

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