@Override
    public long getOldestTombstoneTime() {
      long result = 0;
      if (tombstones.peek() != null) {
        result = tombstones.peek().getVersionTimeStamp();
      }
      return result;
    }
For test purposes only, force the expiration of a number of tombstones for replicated regions.

@param count Number of tombstones to expire
@param timeout the maximum time to wait
@param unit the time unit of the {@code timeout} argument

@return true if the expiration occurred
geode-core/src/main/java/org/apache/geode/internal/cache/TombstoneService.java