code: private String toAttributeName(String vcfInfoFieldKey) {
      String attrName = infoFieldKeyToAttrNameMap.get(vcfInfoFieldKey);
      if (attrName == null) {
        throw new RuntimeException(
            format("Missing attribute for VCF info field [%s]", vcfInfoFieldKey));
      }
      return attrName;
    }
docs: Returns the corresponding attribute name for a VCF info field key
  
  @param vcfInfoFieldKey VCF info field key
  @return MOLGENIS attribute name
  @throws RuntimeException if no attribute could be found for a VCF info field key