@Test(expected=NullPointerException.class)
public void testBuilderBuildNullId() {

    builder()
        .withLineNumber(lineNumber)
        .withChrom(chrom)
        .withPos(pos)
        .withRef(ref)
        .withAlt(alt)
        .withQual(qual)
        .withFilter(filter)
        .withInfo(info)
        .withFormat(format)
        .withGenotypes(genotypes)
        .build();
}