GenericPatientIdExtractor: solve without using FhirPath

[ohr]

GenericPatientIdExtractor uses FhirPatient to extract the Patient reference of a resource. This unfortunately leads to calling parts of HAPI FHIR that may require to include structure libraries (stu3, r4b etc.) that are not used at all. Still it can cause exceptions like:

Caused by: java.lang.ClassNotFoundException: org.hl7.fhir.r4b.model.Resource
	at jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641) ~[?:?]
	at jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188) ~[?:?]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:525) ~[?:?]
	at java.lang.Class.forName0(Native Method) ~[?:?]
	at java.lang.Class.forName(Class.java:375) ~[?:?]
	at ca.uhn.fhir.util.ReflectionUtil.typeExists(ReflectionUtil.java:287) ~[hapi-fhir-base-6.10.2.jar:?]
	at ca.uhn.fhir.context.FhirContext.getValidationSupport(FhirContext.java:716) ~[hapi-fhir-base-6.10.2.jar:?]
	at org.hl7.fhir.r4.hapi.fluentpath.FhirPathR4.<init>(FhirPathR4.java:30) ~[hapi-fhir-structures-r4-6.10.2.jar:?]
	at org.hl7.fhir.r4.hapi.ctx.FhirR4.createFhirPathExecutor(FhirR4.java:45) ~[hapi-fhir-structures-r4-6.10.2.jar:?]
	at ca.uhn.fhir.context.FhirContext.newFhirPath(FhirContext.java:859) ~[hapi-fhir-base-6.10.2.jar:?]
	at org.openehealth.ipf.commons.ihe.fhir.audit.GenericPatientIdExtractor.lambda$patientReferenceFromResource$2(GenericPatientIdExtractor.java:59) ~[ipf-commons-ihe-fhir-core-4.8.0.jar:4.8.0]

[Thopap]

Intesting how this stacktrace could occure?
https://github.com/hapifhir/hapi-fhir/blob/882e7a33ef27996f33bd719130464b0b6e99ec9c/hapi-fhir-base/src/main/java/ca/uhn/fhir/util/ReflectionUtil.java#L287 seems to catch the ClassNotFoundException.