private void verifyDeleteTombstoneStats(BlobStoreStats blobStoreStats, DeleteTombstoneStats deleteTombstoneStats) {
    DeleteTombstoneStats storeDeleteTombstoneStats = blobStoreStats.getDeleteTombstoneStats();
    assertEquals("Mismatch in permanent delete count", deleteTombstoneStats.permanentCount,
        storeDeleteTombstoneStats.permanentCount);
    assertEquals("Mismatch in permanent delete total size", deleteTombstoneStats.permanentSize,
        storeDeleteTombstoneStats.permanentSize);
    assertEquals("Mismatch in expired delete count", deleteTombstoneStats.expiredCount,
        storeDeleteTombstoneStats.expiredCount);
    assertEquals("Mismatch in expired delete total size", deleteTombstoneStats.expiredSize,
        storeDeleteTombstoneStats.expiredSize);
  }
Go over the referenceIndex to collect valid data size information per container. The result is used for
verification purposes.
@param deleteReferenceTimeInMs the reference time in ms until which deletes are relevant
@param expiryReferenceTimeInMs the reference time in ms until which expirations are relevant
@param builder a builder that tracks stats related delete tombstones in log segments.
@return a nested {@link Map} of serviceId to containerId to valid data size
ambry-store/src/test/java/com/github/ambry/store/BlobStoreStatsTest.java