long getStartTime() {
    return startTime;
  }
Loads an existing compaction log from {@link File}.
@param compactionLogFile The compaction log {@link File}.
@param storeKeyFactory The {@link StoreKeyFactory} that is used for keys in the {@link BlobStore} being compacted.
@param time The {@link Time} instance to use.
@param config The store config to use in this compaction log.
@throws IOException
ambry-store/src/main/java/com/github/ambry/store/CompactionLog.java