Support oid data types in resources (Eg STU3 - ImagingStudy)

[sourix]

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Description of Issue

When using extract_entry to extract resources like imagingstudy from a bundle, there is an error that says "Unknown primitive type: org.hl7.fhir.dstu3.model.OidType"

System Configuration

Project Version

0.4.9

Additional Details (optional)

Steps to Reproduce the Issue

1. Use the load_from_directory api to load a bundle that contains an ImagingStudy resource with an uid attribute
2. Attempt to extract the imaging study like so ... imagingstudies = extract_entry(spark, bundles, 'imagingstudy')
3. An error gets thrown with the message "Unknown primitive type: org.hl7.fhir.dstu3.model.OidType"

Expected Outcomes

• Successfully load and extract the ImagingStudy resource type in STU3