Bump org.hl7.fhir.core to 6.4.4

[dotasek]

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[github-actions]

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[madduci]

Hi and thanks for your effort.

Wouldn't be better to target directly the 6.5.x Version of Core Libraries (currently at 6.5.11)?

It seems that there are some breaking changes and the Validator isn't working anymore:

Caused by: java.lang.NoSuchMethodError: 'void org.hl7.fhir.validation.instance.InstanceValidator.<init>(org.hl7.fhir.r5.context.IWorkerContext, org.hl7.fhir.r5.fhirpath.FHIRPathEngine$IEvaluationContext, org.hl7.fhir.r5.utils.XVerExtensionManager)'
	at org.hl7.fhir.common.hapi.validation.validator.ValidatorWrapper.validate(ValidatorWrapper.java:123)
	at org.hl7.fhir.common.hapi.validation.validator.FhirInstanceValidator.validate(FhirInstanceValidator.java:241)
	at org.hl7.fhir.common.hapi.validation.validator.BaseValidatorBridge.doValidate(BaseValidatorBridge.java:23)
	at org.hl7.fhir.common.hapi.validation.validator.BaseValidatorBridge.validateResource(BaseValidatorBridge.java:59)
	at org.hl7.fhir.common.hapi.validation.validator.FhirInstanceValidator.validateResource(FhirInstanceValidator.java:28)

[dotasek]

@madduci Ideally, yes, we should be targeting 6.5.11, and that is the eventual goal.

When doing bumps of this library in the past, I have encountered cases where there are many breaking changes in the underlying logic. These can cause many test failures. In the worst cases, the breaking changes may even interact.

Incrementing in smaller jumps is an attempt to manage a minimal amount of changes in one PR. I have found this safer and easier to review.

@tadgh, I've been using this approach for some time now, and you've reviewed a few of these. Do smaller increments still seem reasonable?

[madduci]

@dotasek I am trying to upgrade to 6.5.13 to use the latest bugfixes from the core library, here: #6769

I've found that some of your changes made in the Parser are useful also for the newer version.

[dotasek]

@madduci I'm happy that you are maintaining your own PR, and will be happy to review it once it passes tests.

Please be aware that this PR is not complete. It still fails many tests, and I am still trying to fix them. Keep this in mind when you develop your own.