### Question:
UK10KVCFHeaderExtender extends VCFHeaderExtender { @Override public void addHeaders(VCFHeader header, String prefix) { addHeadersInfixes(header, prefix, "", ""); if (options.isReportOverlapping() && !options.isReportOverlappingAsMatching()) addHeadersInfixes(header, prefix, "OVL_", " (requiring no genotype match, only position overlap)"); } UK10KVCFHeaderExtender(DBAnnotationOptions options); @Override String getDefaultPrefix(); @Override void addHeaders(VCFHeader header, String prefix); void addHeadersInfixes(VCFHeader header, String prefix, String infix, String note);  }### Answer:
@Test public void test() throws JannovarVarDBException { VCFHeader header = new VCFHeader(); Assert.assertEquals(0, header.getFilterLines().size()); Assert.assertEquals(0, header.getInfoHeaderLines().size()); Assert.assertEquals(0, header.getFormatHeaderLines().size()); Assert.assertEquals(0, header.getIDHeaderLines().size()); Assert.assertEquals(0, header.getOtherHeaderLines().size()); DBAnnotationOptions options = DBAnnotationOptions.createDefaults(); options.setReportOverlapping(true); options.setReportOverlappingAsMatching(false); options.setIdentifierPrefix("UK10K_"); new UK10KVCFHeaderExtender(options).addHeaders(header); Assert.assertEquals(0, header.getFilterLines().size()); Assert.assertEquals(6, header.getInfoHeaderLines().size()); Assert.assertEquals(0, header.getFormatHeaderLines().size()); Assert.assertEquals(6, header.getIDHeaderLines().size()); Assert.assertEquals(0, header.getOtherHeaderLines().size()); Assert.assertNotNull(header.getInfoHeaderLine("UK10K_AC")); Assert.assertNotNull(header.getInfoHeaderLine("UK10K_AN")); Assert.assertNotNull(header.getInfoHeaderLine("UK10K_AF")); Assert.assertNotNull(header.getInfoHeaderLine("UK10K_OVL_AC")); Assert.assertNotNull(header.getInfoHeaderLine("UK10K_OVL_AN")); Assert.assertNotNull(header.getInfoHeaderLine("UK10K_OVL_AF")); }