Fixes #338

[khdesai]

No description provided.

[codecov-io]

Codecov Report

Merging #347 into master will decrease coverage by 0.02%.
The diff coverage is 87.5%.

@@            Coverage Diff             @@
##           master     #347      +/-   ##
==========================================
- Coverage   98.17%   98.15%   -0.03%     
==========================================
  Files         124      124              
  Lines       14182    14170      -12     
==========================================
- Hits        13923    13908      -15     
- Misses        259      262       +3

Impacted Files	Coverage Δ
stix2/v21/sdo.py	94.44% <ø> (-0.1%)	⬇️
stix2/test/v21/test_course_of_action.py	100% <ø> (ø)	⬆️
stix2/v21/observables.py	96.93% <100%> (-0.21%)	⬇️
stix2/test/v21/test_observed_data.py	100% <100%> (ø)	⬆️
stix2/base.py	97.8% <82.35%> (-1.06%)	⬇️

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[clenk]

spec_version is still a required common property on CoA. Also, while the properties have been rolled back to how they were in 2.0, we still need to specify spec_version='2.1' on the common properties. It's not using the 2.0 version of common properties.

[clenk]

confidence and lang are also common properties that should still be present. Sorry; should have noticed that earlier.

[clenk]

Rebased and merged in; thanks @khdesai!