### Question:
AWS4Signer extends AbstractAWSSigner implements ServiceAwareSigner, RegionAwareSigner, Presigner { protected final String getDateStamp(long dateMilli) { return DateUtils.format(DATE_PATTERN, new Date(dateMilli)); } AWS4Signer();  AWS4Signer(boolean doubleUrlEncoding); @Override void sign(Request<?> request, AWSCredentials credentials); @Override void setServiceName(String serviceName); @Override void setRegionName(String regionName); @Override void presignRequest(Request<?> request, AWSCredentials credentials,
            Date expiration);  }### Answer:
@Test public void getDateStamp() { final Date now = new Date(); final String dateStamp = new AWS4Signer().getDateStamp(now.getTime()); final String old = getOldDateStamp(now); assertEquals(old, dateStamp); }