*/
private VariantContext blockToVCF(final HomRefBlock block) {
if ( block == null ) return null;
final VariantContextBuilder vcb = new VariantContextBuilder(block.getStartingVC());
vcb.attributes(new HashMap<String, Object>(2)); // clear the attributes
vcb.stop(block.getStop());
vcb.attribute(VCFConstants.END_KEY, block.getStop());
// create the single Genotype with GQ and DP annotations
final GenotypeBuilder gb = new GenotypeBuilder(sampleName, GATKVariantContextUtils.homozygousAlleleList(block.getRef(),block.getPloidy()));