Bugfix, filter nulls in getPrimaryTermId

[leokim-l]

bugfix, keep allowing null but filter for it and expand warning description. Otherwise running the code with old HPO might crash, which is a bit too strong

[leokim-l]

Daniel pointed out this method should not be static (tied to class, not instance), or if called without an instance (which triggers the constructor) it will lead to a null pointer exception. Since it is closely related, I will fix this in this PR and then mark it ready for review again.

BOQA/boqa-core/src/main/java/org/p2gx/boqa/core/internal/OntologyTraverser.java

Lines 122 to 123 in 195e131

	public static TermId getPrimaryTermId(TermId t){
	TermId primaryTermId = hpo.getPrimaryTermId(t);

[ielis]

The code looks IMO better, I like that the Ontology is not static anymore.

However, if would be superior to only have one constructor in PhenopacketData - a constructor that simply takes all the fields. The logic that depends on hpo can then be moved either into a static method on PhenopacketData or to some other class (the class for mapping a phenopacket to PatientData).

This would simplify making naive PhenopacketData instances for testing, and IMO structure the code better.

But, it's a minute change. Please implement if you find it useful.