When attempting to parse a referenced VCF file, it might be possible for GenomicStudyAnalysis to contain sufficient metadata to enable a safe parse. In particular, we use genomic source class (e.g. does the VCF file contain only germline variants, only somatic variants, or a mix) and VCF sample column (e.g. in a multi-sample VCF such as a tumor-normal VCF, which sample column in the VCF contains the patient variants) when converting VCF to FHIR. 

While it might make sense to add a genomicSourceClass metadata field, it may also be that we need a flexible key-value mechanism that allows a lab to include test specific parameters.