Handle null in stream processing

[lincmba]

fixes #104
Engineer Checklist

• I have written Unit tests for any new feature(s) and edge cases for
  bug fixes
• I have added documentation for any new feature(s) and configuration
  option(s) on the README.md
• I have run mvn spotless:check to check my code follows the project's
  style guide
• I have run mvn clean test jacoco:report to confirm the coverage report
  was generated at plugins/target/site/jacoco/index.html
• I ran mvn clean package right before creating this pull request.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 4 lines in your changes missing coverage. Please review.

Project coverage is 61.54%. Comparing base (2c88ffe) to head (274e0c1).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...teway/plugins/LocationHierarchyEndpointHelper.java	72.72%	1 Missing and 2 partials ⚠️
...way/plugins/PractitionerDetailsEndpointHelper.java	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #106      +/-   ##
============================================
+ Coverage     60.44%   61.54%   +1.10%     
- Complexity      202      206       +4     
============================================
  Files            16       16              
  Lines          1408     1412       +4     
  Branches        162      164       +2     
============================================
+ Hits            851      869      +18     
+ Misses          476      458      -18     
- Partials         81       85       +4     

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