private String getVcfName(Predicate<? super VcfInfo> vcfPredicate, List<VcfInfo> vcfList) {
   if (this.allowMissingFiles) {
     VcfInfo dummy = new VcfInfo();
     dummy.setFileName("");
     dummy.setIndexFileName("");
     dummy.setObjectID("");
     dummy.setIndexObjectID("");
     VcfInfo v = vcfList.stream().filter(vcfPredicate).findFirst().orElse(dummy);
     return v.getFileName();
   } else {
     return vcfList.stream().filter(vcfPredicate).findFirst().get().getFileName();
   }
 }