Fix extraction for choice type values

[jingtang10]

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Fixes #[issue number]

Description
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• I have read and acknowledged the Code of conduct.
• I have read the Contributing page.
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• I have discussed my proposed solution with code owners in the linked issue(s) and we have agreed upon the general approach.
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[kevinmost]

LGTM with 1 nit

[codecov]

Codecov Report

Merging #1352 (214fad5) into master (8d5bc32) will increase coverage by 0.03%.
The diff coverage is 72.72%.

@@             Coverage Diff              @@
##             master    #1352      +/-   ##
============================================
+ Coverage     84.60%   84.64%   +0.03%     
- Complexity      699      701       +2     
============================================
  Files           148      148              
  Lines         10719    10726       +7     
  Branches        853      854       +1     
============================================
+ Hits           9069     9079      +10     
- Misses         1228     1229       +1     
+ Partials        422      418       -4     

Impacted Files	Coverage Δ
...android/fhir/datacapture/mapping/ResourceMapper.kt	85.50% <72.72%> (+2.00%)	⬆️

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