Provide a more permanent solution and test for the HAPI FHIR caching issue

[mkalish]

User Story

As a dev, I would like to always be able to use FhirPathUtils without having to worry about concurrency.

Description/Use Case

There is a defect in the HAPI FHIR library that can cause errors when FhirPathUtils is used concurrently. See this for more details

Risks/Impacts/Considerations

Dev Notes

• Hopefully this is something that the HAPI FHIR team can fix and would mean that this ticket would be simply just upgrading the library.

Acceptance Criteria

• [ ] One line of code can't be deleted and break production
• [ ] A test is written so that the issue won't crop up again

[Andrey-Glazkv]

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[Andrey-Glazkv]

Hey team! Please add your planning poker estimate with Zenhub @adegolier @jalbinson