static LogSegmentName getRandomLogSegmentName(Collection<LogSegmentName> excludedNames) {
    LogSegmentName segmentName;
    do {
      long pos = Utils.getRandomLong(TestUtils.RANDOM, 10000);
      long gen = Utils.getRandomLong(TestUtils.RANDOM, 10000);
      segmentName = LogSegmentName.fromPositionAndGeneration(pos, gen);
    } while (excludedNames != null && excludedNames.contains(segmentName));
    return segmentName;
  }
Get a random log segment name that does not conflict with the names in {@code excludedNames}
@param excludedNames names that are already reserved for other segments, or null if there are no excluded names.
@return the name.
ambry-store/src/test/java/com/github/ambry/store/StoreTestUtils.java